1. Substantive Rules

The origin of the practice remains murky,Footnote ⁵ but lining up is now an ever-present feature of modern life.Footnote ⁶ Queues arise informally and spontaneously, but closer analysis reveals that four interrelated social norms constitute this social practice. The first is form a line. That is, when waiting, the proper way to do so is to stand directly in back of the person who began waiting just before you, forming a straight line (as opposed to a scrum, or a mob, or a double helix). The queue provides a very clear physical signal of ordinality, indicating unambiguously where each person's priority spot belongs relative to each other's.Footnote ⁷ The second basic maxim of the line invokes the most visceral reactions: no cutting. Once the line is established, you may join it only by going to the back and lining up behind the last person. Intruding into the line at any other point, especially toward the front but even at the rear, is not permitted and often harshly sanctioned. Norms against line jumping are so strongly felt that people frequently regard no cutting as a point of national pride,Footnote ⁸ and even a core principle of human decency.Footnote ⁹ The third core principle of the line is a corollary of the first: first come, first served (FCFS). This tenet determines the scope of a line-waiter's entitlement: a right to be served in the order of his or her spot in the queue, roughly tracking property law's first possession principle.Footnote ¹⁰ A spot in line thus becomes “a kind of mobile property in land, a portable space which is uniquely and recognizably his or hers and is defensible against all comers” (Gray Reference Gray, Alexander and Peñalver2010, 4). The foregoing norms determine the acquisition of a place in line and the nature of a line-waiter's entitlement. A fourth rule, wait your turn, dictates both how to maintain your space in line and what conduct may lead to losing it. The first valence of wait your turn is straightforward: keeping your line priority requires ongoing physical possession of your place in the queue.Footnote ¹¹ It is not enough to simply show up, claim a space, and leave to go wait in a more comfortable place; you have to stay and wait in that physical place in order to maintain your priority (Mann Reference Mann1970; Brady Reference Brady2002). Queue priority is thus not just about being earlier in time, but about continuing to signal your priority claim by virtue of your physical presence (Brady Reference Brady2002, 161). Wait your turn thus also implies a strict principle of abandonment: if you leave the line, you lose your space, period.Footnote ¹² Departing the line means you immediately forfeit your priority, just as abandoning your property means you have relinquished legal ownership of it (Hansen Reference Hansen2010).

2. Sanctions, External and Internal

These rules may lack the force of law, but violating them may still lead to state sanctions under some circumstances.Footnote ¹³ While the overwhelming majority of people simply join queues politely, when they do not, the primary penalty comes in the form of external sanctions—namely, opposition from other line members. Popular accounts of violations of no cutting, for example, reveal a variety of responses. One English line vigilante reports that when a pushy businessman barged in back of him in a line for public transport and refused to leave, the line-waiter simply allowed everyone else in line to cut ahead of him and the businessman just to teach the latter a lesson.Footnote ¹⁴ Similarly, the pilot episode of the television series 30 Rock featured lead character Liz Lemon in a conflict with a man who she felt had cut in line at an outdoor hotdog cart. Her solution: buying all the hotdogs and distributing them to the people who had waited patiently in line, making sure the queue-jumper got nothing. One etiquette consultant suggested photographing line-cutting “miscreants” and engaging in online shaming via social media (Grotts Reference Grotts2013).

Some empirical studies have assessed violations of no cutting, finding results that match these narratives. In famed social psychologist Stanley Milgram's final study, he had confederates intrude into waiting lines and found responses ranging from verbal objections to violence (Milgram Reference Milgram1986, 684).Footnote ¹⁵ Milgram and others have found that the responsibility for enforcing the no-cutting rule usually falls on the person directly in back of the cut. The likelihood that someone will object to queue jumping thus falls off dramatically farther back in the line from the intrusion. The research on line intrusion shows that not all line-cutters will be sanctioned. In Milgram's study, for example, even when someone cut directly in front of someone else in a queue, the intrusion met with total indifference around 25 percent of the time, and met with an aggressive physical objection—such as a firm tap on the shoulder or a shove out of the queue—only about 10 percent of the time (Milgram Reference Milgram1986, 684). But in that relatively small number of cases where violence erupts, things can go very wrong, very quickly. Local news outlets frequently report episodes of “line rage” resulting in fights or worse. A woman waiting in line at a St. Louis pawn shop, for example, savagely assaulted another woman who had cut in front of her in the service queue (Huda Reference Huda2014).Footnote ¹⁶

Service providers themselves may also monitor line cutting and impose penalties for it. The park policies of Six Flags Over Texas, for example, warn that “line jumping” is conduct that is “offensive to park guests and may be cause for ejection without refund.”Footnote ¹⁷ Six Flags Over Georgia has a hotline that patrons can call to report line cutting, and its employees often follow through with complaints by ejecting line jumpers or at least making them go to the end of the queue.Footnote ¹⁸ Police may participate in enforcing line integrity, especially where the line intruder is disruptive enough that the conduct may amount to a substantive crime like assault (of other queue members) or disturbing the peace (Marco 2009). This kind of police support of line norms is not always available; people who complained to the Capitol Police about impermissible intrusion into waiting lines for Supreme Court arguments were disappointed to meet with near-total indifference (Blackman Reference Malady2013).

Not all sanctions operate externally. As Robert Cooter has observed, nonlegal regulatory systems persist also because of internal sanctions (Cooter Reference Cooter1996, 1694). Internalized norms will lead people to follow norms due to negative emotions like guilt or positive ones like a desire to participate in constructive social behavior. Milgram's line-intrusion experiment inadvertently showed the strength of internal sanctions in queue norms. His experimental intruders procrastinated at length, paced nervously near the line, and took as much as a half-hour before working up the nerve to intrude into the queue (Milgram Reference Milgram1986, 685–86). When they did, they often exhibited physical symptoms such as “pallor and nausea” due to “the inhibitory anxiety that ordinarily prevents people from breaching social norms” (Milgram Reference Milgram1986, 686).Footnote ¹⁹

3. Exceptions

The norms of the queue bear a number of exceptions, of which the most familiar permits line jumping in cases of necessity. When check-in waits at the terminal grow long, for example, many airlines seek out customers who are due to leave soon and allow them to move to the front of the line so they do not miss their flights (Allon Reference Allon2012). Emergency-room protocol sensibly allows patients who have suffered serious injuries or heart attacks to be seen ahead of longer-waiting folks with mere sprained ankles or stubborn sinus infections (Perry and Zarsky Reference Perry and Zarsky2014, 1646–47). Necessity may also furnish ad hoc exceptions to wait your turn. As we have seen, very long lines employ shift systems and otherwise relax the physical occupancy principle when queues last so long that people cannot reasonably be expected to remain standing for the duration of the wait. Most people agree that even in shorter lines, departures from queue norms can be tolerated (typically after receiving permission from people adjacent in the line) to accommodate concerns about things like health, disability, or child care, so long as the exception is requested and approved by one's line-waiting neighbors (Dehn Reference Dehn2006, 4–14). All these exceptions flow from the same intuition that underlies other necessity defenses in law.Footnote ²⁰ We depart from line norms in the relatively rare cases when the marginal cost of upsetting the traditional order of the queue is overborne by far weightier concerns, such as disrupted travel, serious health concerns, or the demands of the human excretory system (Sugarman Reference Sugarman2005).

Not all lines are created equal, and thus not all line norms operate in quite the same way. For example, queues to get tickets for major sporting events or long-awaited movie premieres last for many hours or even days.Footnote ²¹ The major variation in these lines relates to wait your turn, where necessity leads to greater tolerance for departures from the physical line. Leon Mann's classic work on the days-long queues for tickets to the Australian Rules Football Grand Final found norms permitting people to leave a placeholder like a box or a sweater to represent their place (Mann Reference Mann1969, 345; Brady Reference Brady2002, 158–59). Lines that last a long time may also exhibit shift systems, where an entire group lays claim to a space, permitting all group members to keep the space so long as some members remain to physically occupy it.Footnote ²² For example, students waiting in K-ville to see Duke basketball games queue in groups (sometimes resulting in an elaborate tent city), and norms permit some members of each group to rotate out at a time so they can get food, attend class, and escape the inclement winter weather,Footnote ²³ but strict norms still cabin these modified approaches to wait your turn. The place-marker system allows only brief departures from line (Brady Reference Brady2002, 159), and others in line will heavily sanction its abuse—including by destroying markers left by those absent from the line and refusing to let them retake their space (Mann Reference Mann1969, 346).Footnote ²⁴ Missing even a single tent check in K-ville, for example, means losing your place in line, with no exceptions.Footnote ²⁵

In these more extensive queues, the need to maintain order among larger groups also warrants not only more elaborate norms but also the development of systems to administer them. In the long lines for general-admission access to concerts by cult bands like Pearl Jam or U2, certain individuals—often particularly hardcore fans—will emerge to make sure that others in line comply with increasingly complex line norms (Helweg-Larsen and LoMonaco Reference Helweg‐Larsen and Barbara2008, 2380). But these norms pale in comparison with the formality and complexity of those governing K-ville. Since they first emerged in the mid-1980s, the protracted lines for tickets to Duke men's basketball games have become a university institution (Sarowitz Reference Sarowitz2001). The elaborate norms governing these queues are contained in a twenty-five-page document that determines such issues as how many members of a tenting group must be present at all times (one-fourth), which restrooms may be used by those waiting in line (preferably the porta-potties provided for K-ville, but failing that those in the IM Gym), and even where blue body paint must be applied (only on soft surfaces such as grass). K-ville also requires numerous people to enforce its byzantine rule structure. Line monitors, for example, perform random checks to make sure groups have enough members waiting in each tent to retain their place.Footnote ²⁶ There is even a formal administrator in charge of K-ville and its rules who enjoys a cabinet-level position in the Duke student government.

4. Disconsensus

While most people—or at least, most people in high-queuing cultures—agree on the foregoing basic rules of waiting in line, zones of disagreement remain. The most contentious of these is “subinfeudation”:Footnote ²⁷ having one member of a group stand in line, and then invite in the rest of the group only when the point of service draws near. The advantages of this approach for the subgroup are obvious (all members get to the front of the line with only one having to wait), but other members of the line typically contest its fairness. After all, subinfeudation permits the nonwaiting group members to advance to the front of the line without doing the hard work of standing, violating both FCFS and wait your turn. As a result, most institutions formally ban this practice. The official park policies of Six Flags Over Texas exemplify the strong no-subinfeudation view, forbidding “saving places in line … for any reason.”Footnote ²⁸ Robert Samuel, the founder of the line-waiting service Same Old Line Dudes (SOLD) requires that clients pay for one line-waiter for every person who will take a place in the queue because violating the “even ratio” approach would risk retaliation by other queue members (Yannetta 2014).Footnote ²⁹ In 2007, violence broke out when a woman at a Missouri Wal-Mart joined her cousin in a checkout line, leading to a violent, racially charged fracas as well as the line-cutter's arrest and eventual guilty plea to two misdemeanors (Mattingly and Smith Reference Mattingly and Smith2009).

Yet the norms around subinfeudation remain conflicted. Unlike with cutting, anecdotal reports of subinfeudation are frequent. Disney officials, for example, report that outright cutting into lines is rare at their amusement parks, but complaints about subinfeudation persist and remain their leading queue-related complaint.Footnote ³⁰ In some settings, subinfeudation is encouraged, as in India's gender-segregated lines, when men are expected to join their wives in the “ladies' queue” (Basu Reference Basu2004). The widely accepted shift systems that arise in longer lines such as Duke's K-ville are essentially modified versions of subinfeudation, in that they allow some members of a group to reserve a line spot for many others. By contrast, people in the very long lines for general access admission to Pearl Jam concerts widely agreed that people in line could not have even one person join them, even if it was a spouse who was coming straight from work.Footnote ³¹ A recent attempt at drafting a hypothetical “Queue Bill” sought to resolve the disconsensus about subinfeudation by proposing that each member of a line should be permitted to let one and only one person to join her, on the condition that those invited to join did not have the privilege of inviting anyone else to join the queue (Dehn Reference Dehn2006).

1. Cultural Variation

Within some cultures, the practice of queueing as outlined above is taken for granted. Americans, for example, tend to take the norms of the queue very seriously, and treat them as having independent moral force. One US observer stated that “[c]utting in line is cheating, and everyone knows it. Children know it most acutely, know it in their bones” (Junod Reference Junod2012). Sweden also ranks among the world's highest-queuing societies (Kelly Reference Kelly2009), and at the height of the Nigerian oil shortage in the late 1970s, patrons at petrol stations waited in well-organized lines despite the pressure of a resource crisis (Wiseman Reference Wiseman1979, 317–19). But not all nations take the queue this seriously. For example, concern for queue priority in Switzerland is low, and lining up is not standard practice when waiting for service.Footnote ³² In fact, when the Swiss postal service sought to implement single waiting lines in its banks, government officials and customers alike roundly objected (and all eventually compromised on a numbered waiting system). Mainland China also tends to be a lower-queuing culture,Footnote ³³ so much so that prior to the 2008 Beijing Olympics, the government engaged in a norm-building program to encourage its citizens to form and wait patiently in lines for public transportation and events (Macartney Reference Macartney2007). However, at least according to anecdotal evidence, the practice of lining up in Mainland China does not appear to have taken off after the Beijing Olympics.Footnote ³⁴ Like all cultural generalizations, these claims should be taken with a liberal dose of salt. British self-congratulation about orderly queuing does not seem to account for the tendency of Londoners to rush up to tube cars and bendy-buses regardless of how long they have waited (Winterman Reference Winterman2013). In crowded US bars, bartenders serve patrons regardless of FCFS, perhaps because of the disorder introduced by patrons' inebriation. And some firsthand observations from China report that respect for queues has seen some improvement in recent years.Footnote ³⁵

Still other cultures favor entirely different approaches to securing priority in waiting situations. Take-a-number systems, such as the kind recently implemented at banks in Tehran,Footnote ³⁶ require more front-end investment, but provide clear priority to customers and avoid the discomfort of having to stand in a queue. Many countries, especially Latin ones, advert to a more informal, but still reasonably effective, systems of order whereby a person entering a waiting situation asks the group, “who's last?” (hence the Spanish name of the system, quien es ultimo?), and then takes care to approach the point of service after the person preceding them (Fernandez Reference Fernandez2013). This approach secures priority not by creating the physical representation of ordinal priority, but by depending on interpersonal monitoring among line members. As long as each person vouches for the person whose turn follows theirs, quien es ultimo works well—and indeed we sometimes see use of this protocol even in strong-queuing cultures where only a few people are waiting for service. Quien es ultimo suffers by comparison to the queue in that it fails to give clear visual signals of one's relative place in line, since you know only who precedes you, not how many people precede them. It is also not useful when the number of people waiting is high, since in a large mob people will lose track of the individual immediately before them.

2. Service Providers

Those waiting in line typically insist on strict adherence to FCFS, except when the provider of the service or good for which everyone is waiting permits systematic deviations from this norm (Schmitt, Dubé, and Leclerc Reference Schmitt, Laurette and France1992, 811; Alexander Reference Alexander2012, 877–80).Footnote ³⁷ Service providers frequently favor some classes of customers with shorter lines or the ability to skip waiting altogether. Disneyland, for example, is one of many amusement parks that permits patrons with disabilities to stand in shorter lines (or skip lines altogether). Another familiar variant on this approach is to favor with shorter lines customers who pose lighter service demands, such as express lanes in supermarkets for shoppers with ten or fewer items. These deviations from FCFS are rooted in concerns about fundamental fairness (e.g., accommodating the heightened difficulty disabled patrons may have waiting in line) or efficiency (e.g., calibrating wait times and service demands by allowing customers who require less attention to wait less time for service). By contrast, though, some service providers may permit preferred customers to experience reduced or no wait time due to “elite” status. Airlines, for example, allow those who buy first-class tickets or earn frequent-flyer status to enjoy shorter security-line waits and early boarding privileges. Bouncers for fashionable nightclubs permit especially good-looking or well-connected people to enter the venue regardless of their place in the waiting queue. These exceptions to FCFS possess less intuitive appeal because they not are rooted in widely understood or shared concerns like need or speed of service, but serve rather as a tool for the service provider to encourage consumer demand or to cherry-pick a desired clientele. Yet in none of these instances do those in line object to deviation from FCFS,Footnote ³⁸ suggesting that businesses' capacity to deliver goods and services on their preferred terms trumps organic queue norms (Schmitt, Dubé, and Leclerc Reference Schmitt, Laurette and France1992, 811).

3. Queue Markets

Another factor complicating queue norms is the increasing commercialization of waiting in line. This practice first arose in Washington, DC, where the small number of public seats available for Supreme Court arguments and congressional hearings produces long—sometimes overnight—waits outside federal buildings (Copeland Reference Copeland2005).Footnote ³⁹ Since the 1990s, several companies have made available employees who will secure one of these coveted seats by queuing in exchange for an hourly rate (Kliff Reference Kliff2012).Footnote ⁴⁰ For decades, paid line waiting remained peculiar to Washington political events, but it has quite recently become prevalent in the private sector as well. Consumers can now hire employees of New York's SOLD or TaskRabbit.com to wait in line for the latest iPhone, Black Friday sales, or even a coveted cronut (Pinsker Reference Pinsker2014; Zhang Reference Zhang2014). Also at the nexus of lines and markets is the “VIP line” approach to queues. Knott's Berry Farm, for instance, sells a “hate to wait” pass that allows patrons willing to pay a greater admission charge the privilege of skipping to the front of three lines for the park's thrill rides (MacDonald 2010). Universal Studios offers a “front of the line” pass that permits visitors to skip to the front of the queue once at each of the park's rides.

These practices appear to violate foundational queue norms such as wait your turn and FCFS, and they are far from universally beloved. Cultural critics have observed that the prevalence of VIP line privileges introduces a visible degree of social stratification that can degrade the amusement park experience for those who cannot afford them (Junod Reference Junod2012). One study of patrons' attitudes toward VIP lines confirmed that while they enhance the experience of those who have access to them, they generate bitterness and a negative attitude toward the venue in those who do not (Alexander Reference Alexander2012). These concerns are exacerbated when the commercialized line is for a public event rather than merely a private amusement park. Michael Sandel has suggested that paid line waiting for Supreme Court arguments or congressional hearings affronts essential democratic principles of equality among citizens by making access to democratic process dependent on one's ability to pay for it (Sandel Reference Sandel2012, 33–35). The Supreme Court has recently endorsed this view, issuing an advisory rule preventing paid line-standers from keeping proxy places in the lawyers' line for oral argument seats.

Yet despite this expressed distaste, the commercialization of queues grows increasingly common and sees none of the informal sanctions that accompanies deviation from line norms. What explains the toleration of this trend, despite serious concerns about it? In terms of paid line waiting, the private side of the practice has engendered relatively little expressed objections. This may be an incident of the property-like character of line spaces, which once acquired include not only a right to exclude others, but apparently also a right to transfer (Grotts Reference Grotts2013). Line-waiting services are careful to avoid abuses of their services, scrupulously requiring that clients must hire a separate employee for each individual who plans to join the line—a policy that the proprietor of SOLD credits with avoiding any objections from others in line (Zhang Reference Zhang2014). Paid queuing for events that are part of democratic processes raises weightier concerns than markets in lines for iPhones or cronuts, but remains difficult to prevent. It is far from clear who among those waiting in the long lines outside the Supreme Court is a for-hire line-waiter or just a citizen especially interested in the upcoming argument (Kliff Reference Kliff2012). Considering that the paid-waiting industry has persisted for nearly thirty years, it is unclear whether the practice even violates queue norms (unlike the clear consensus against, e.g., line cutting), or has become implicitly accepted over those decades. VIP queues likely persist for this latter reason as well. While they engender resentment and likely take away from the experience of regular patrons, they are official policies of the amusement parks that provide them. This means that while most customers may dislike them, VIP queues do not represent norm violations—or at least they illustrate again that patrons defer to service providers over informal social rules.

4. Technological Interventions

The queue is a familiar, but also somewhat dated, means of organizing waiting. In recent years, technological interventions have rendered certain kinds of queues a thing of the past. The long lines that used to form for concert tickets no longer arise now that TicketMaster.com permits people to compete for desired concert seats from the comfort of their Internet-connected homes. Google recently added a feature called “Popular Times” to its maps application that will allow users to see how long a line is at a given business establishment (Lufkin Reference Lufkin2015). This will not eliminate queues—if you have just the noon hour for lunch, the app will not make that particular queue any shorter—but it will reduce waits by causing people who prefer to avoid long lines to avoid them, and will allow consumers with flexibility to distribute their consumption to lower-demand times. On the other hand, apps like Preo allow circumvention of lines altogether. They enable customers to preorder food and drinks, and then pick it up from an express counter rather than waiting in line to order and then waiting again for their order to be prepared (Baker Reference Baker2014). One could also imagine more direct technological interventions in lines. Consider, in light of the aforementioned acceptance of queue markets, an app that allowed people in a given line to bargain away spaces they do not value very highly to those behind them in the queue, or even outside it altogether, who place a higher value on them. Technology could facilitate this kind of Coasean reordering of queues, allowing people in line to discreetly sell and swap their spaces via smart phone. All these innovations promise to reduce the inefficiencies of the waiting line; however, a fully connected future may be queue-free. Apps could allow patrons to place themselves on virtual queues for service, and the provider could simply ping users when their turn has arrived, rendering the standing line a thing of the past.

***

This section explored the informal order of the social practice of waiting in line. While there is general consensus about the essential rules that govern this practice, there are also numerous exceptions and variations, as well as disconsensus, especially between groups and across cultures. The answer to this descriptive inquiry raises a more difficult one: Why does this form of social order arise and persist? The following section takes on this question, investigating the queue in light of leading theories of social norms and recent advances in behavioral research to craft an explanation.

1. From Bad Men to Strong Reciprocators

One vision of the legal actor that finds favor in legal scholarship is homo economicus, the Millian construct that presumes people are invariably concerned only about maximizing their self-interest.Footnote ⁴⁶ This intuition finds acceptance as an assumption of, for example, classical law and economic approaches to crime and social organization (McAdams 1997, 1650), but recent evidence has revealed that it fails to completely describe human behavior. Psychologists and sociologists have convincingly shown that people are not solely self-interested individuals who are looking out only for themselves at the expense of others, but are in fact strong reciprocators whose first inclination is to contribute to group well-being, even if it comes at some cost to them (Goulder Reference Goulder1960; Titmuss Reference Titmuss1971). “A strong reciprocator,” as Herbert Gintis explained, “is predisposed to cooperate with others and punish non-cooperators, even when this behavior cannot be justified in terms of self-interest, extended kinship, or reciprocal altruism” (Gintis Reference Gintis2000). Ernst Fehr elaborated on this notion, distinguishing in particular positive and negative reciprocation: “[a] person is a strong reciprocator if she is willing (i) to sacrifice resources to be kind to those who are being kind (= strong positive reciprocity) and (ii) to sacrifice resources to punish those who are being unkind (= strong negative reciprocity)” (Fehr et al. Reference Fehr, Urs and Simon2002).

Studies from a range of societies undertaken under many different conditions show that while not all humans are strong reciprocators, this tendency is widespread within populations and across cultures. The best evidence for this comes from the classic public goods game. In this experiment, subjects in groups of four are each given a number of points, redeemable at the end of the experiment for real money (Fehr and Gachter Reference Fehr and Gachter2000). In the standard treatment, each subject must place some amount of his or her choosing in a common account, and keep what remains in the subject's private account. The experimenter then tells the subjects how many total points were contributed to the common account, and adds to each private account 40 percent of this total. The optimal strategy to maximize one's own gains is simple: donate nothing (Gintis Reference Gintis2000, 171). Yet surprisingly, test subjects in public goods games actually start off sharing generously, giving on average half their private account to the common account, as the strong reciprocity account would suggest. This level of contribution tends to decline over time, though, and after ten rounds, most players behave in an entirely self-interested manner, often contributing nothing to the common account (Fehr and Schmidt Reference Fehr and Schmidt1999). As the strong reciprocator model would predict, the reason given by cooperative subjects for their increasing noncooperation is that they felt angry at others who contributed less than they did, and lowered their contributions as a way of punishing them (Andreoni Reference Andreoni1995). Indeed, in public goods games where subjects are allowed not only to withhold contributions to the common account, but also to fine noncooperative players, subjects consistently take this opportunity to punish—even at a cost to themselves (Ostrom et al. Reference Ostrom, James and Roy1992). Related studies found that employees who received what they perceived to be a fair wage tended to do a good job even if they were paid before performing any work and had no chance of interacting with their employer again (Gintis Reference Gintis2000, 155–57). A host of other studies have provided even more support for the strong reciprocator model (Guth and Tietz Reference Guth and Tietz1990; Camerer and Thaler Reference Camerer and Thaler1995; Roth Reference Roth, Kagel and Roth1995).

The notion of strong reciprocity must be disaggregated into its positive side, where people tend to cooperate instinctively (“positive reciprocity”), as well as a negative side, where people tend to retaliate against those who defect from norms (“negative reciprocity”). As the experimental evidence indicates, the tendency toward positive reciprocity may be our default setting (Dohmen et al. Reference Dohmen, Armin, David and Uwe2009), but is neither immutable nor without limit. “Individuals prefer to contribute if they believe others are contributing,” as Dan Kahan explained, “but they will free-ride if they believe others are inclined to free-ride” (Kahan Reference Kahan2003). Most people default toward cooperation and will go along with norms, until and unless they perceive free riding. But while the tendency toward cooperation is widely shared, the commitment to cooperation in the presence of defection is not. Some are particularly likely to cease reciprocating at the first suggestion that others are defecting; while others will reciprocate even in the presence of a relatively high level of perceived cheating. There are also the pernicious folks who will always cheat to benefit themselves regardless of group norms, and the Mother Teresa types who continue reciprocating even when norm systems have collapsed and everyone else is simply looking out for their own interests (Kahan Reference Kahan2003).

Researchers investigating the human tendency toward positive reciprocity have thus found that the strongest driver of collective behavior is not the threat of punishment for deviation, but a sincerely held belief that others are reliably reciprocating as well (Blank Reference Blank2011).Footnote ⁴⁷ With tax compliance, for example, there is almost no relationship between the harshness of penalties and the rate at which people pay their tax bill (Cooter and Eisenberg Reference Cooter and Eisenberg2001, 1725).Footnote ⁴⁸ But what does predict whether people will pay their taxes? As the strong reciprocator model would suggest, the answer is: whether they perceive other people to be paying their taxes (Kahan Reference Kahan2003). One study found that when a group of people was informed that the general rate of tax compliance was much higher than is commonly assumed, members of that group reported more income and claimed fewer deductions than individuals in a control group (Coleman Reference Coleman1996). By contrast, in some European countries—Russia and Greece in particular—it is widely believed that no one pays taxes unless personally threatened by the government with penalties. The result is a much lower rate of tax compliance. Other research has borne out this conclusion. Lior Strahilevitz, for example, explained the willingness of anonymous users of pre-Grokster peer-to-peer networks to share sound recordings in terms of a generalized perception that most other users shared files (Strahilevitz Reference Strahilevitz2003b, 563–71).

The strong reciprocator model predicts that people will not only cooperate positively when others do likewise, but also that they will punish defectors, even at substantial personal cost (Fehr et al. Reference Fehr, Urs and Simon2002, 2). Subjects in public goods games, for example, will spend their own resources just to punish those they perceive to be insufficiently cooperative (Ostrom et al. Reference Ostrom, James and Roy1992). A large-scale study of both positive and negative reciprocity found that these qualities exist independently of one another (Dohmen et al. Reference Dohmen, Armin, David and Uwe2009, 599), and that positive reciprocators tend to be happier and more materially successful than negative reciprocators. However spiteful and pointless the tendency toward negative reciprocity may seem, research has shown it to have surprising social benefits (Friedman and Singh Reference Friedman and Singh2004, 157–58), especially when retaliation is carefully targeted in a way designed to signal general disapproval of noncooperative behavior (Kahan Reference Kahan2003, 10).

The strong reciprocator model provides the best explanation for why people wait in line.Footnote ⁴⁹ Lines represent a classic form of collective action in which a large number of people engages in conduct that benefits the overall group (waiting politely, respecting priority) while resisting purely self-interested behavior (cutting in front of others).Footnote ⁵⁰ The strong reciprocator model suggests that people do not queue up because they fear punishment, or because they are mindlessly following an amoral coordination practice, or because they seek status or economic benefits from others in line. Rather, it suggests simply that standing in line is primarily a classic expression of the kind of adherence to cooperative norms that is part of our psychological makeup (Fehr et al. Reference Fehr, Urs and Simon2002, 16–18). This model also explains the outsized “queue rage” that we see when rude people try to cut into lines, even when the cut does not inflict any delay on the enforcer, because it suggests that the instinct to punish norm violations does not come only from a sense of seeking compensation for harm inflicted by the norm violation (Gintis Reference Gintis2000, 177). Finally, and most importantly, strong reciprocity also accounts for something that other theories cannot: the tendency of people to honor these queue norms even among strangers (Gintis Reference Gintis2003). Unlike, for example, reciprocal altruism, this theory suggests that people will cooperate even at personal cost and in the absence of any expectation of future reward—which is precisely what happens countless times every day in waiting lines (Malady Reference Malady2013).

But in order to be confident that the strong reciprocator theory accounts for widespread obedience to queue norms, we have to explore two further issues. First, the strong reciprocator model does not (indeed, cannot) predict a high degree of cooperation unless people recognize the presence of cooperative behavior in the first place. So for strong reciprocation to explain the social practice of queuing in societies where it is prevalent, there must be a widespread perception that queue norms exist and are widely followed. Second, informal systems of order are stable but vulnerable to collapse in the presence of widespread defection. This raises a pair of questions: Why don't we see committed defectors cutting in line more often? Why doesn't even a low level of defection destabilize, or undermine entirely, the institution of the queue?

2. Strong Reciprocators and Super-Salient Signals

Strong reciprocity leads people to cooperate reflexively, even when it would be in their immediate self-interest not to, so long as they believe that others are cooperating as well. In some cases, this belief can come from active information dissemination, such as civic campaigns that inform residents of a municipality that their neighbors are pursuing recycling strategies (Carlson Reference Carlson2001, 1290). Peer-to-peer file-swapping systems convinced their anonymous, loose-knit users to share their files by telling them that the clear majority of users voluntarily chose to do so as well (Strahilevitz Reference Strahilevitz2003a). However, the practice of waiting in line is a broad and diffuse social practice, not limited to a particular place or online community, so there can be no central administrator to inform people of their obligation to queue politely. So if widespread obedience of line norms depends on the belief that other people are also cooperating with them, where does this belief come from?

The belief comes from the physical waiting line itself. Lines are intrinsically expressive phenomena that by their very existence communicate the fact of widespread cooperation in a way that triggers the instinct to reciprocate. Queues crop up repeatedly throughout our daily lives, providing an object lesson in how their norms work and, more importantly, signaling the fact that people cooperate with them. The operation of a line communicates to observers an overwhelming degree of deference to the elemental norms that govern queue conduct. The presence of a physical waiting line in itself expresses that the line—as opposed to a race or a mob or quien es ultimo—is the appropriate form of social organization when faced with shortages of service provision (form a line). The provision of service to earlier arrivals expresses widespread agreement that queues should be organized by a principle of ordinal priority rooted in first possession principles (FCFS). The visible willingness of people in line to queue up, even despite the discomfort and anxiety generally produced by the act of waiting, expresses the rule that we should respect the priority order of the line (wait your turn) even when it is costly and unappealing to do so. And the general absence of people jumping the queue expresses the pervasiveness of the prohibition against that practice and the socially offensive nature of queue jumping (no cutting).

The physical form of the line itself also serves as a particularly powerful device for communicating cooperation. The line itself embodies to onlookers the notion of unspoken cooperation among strangers, with anywhere from a few to a few thousand materialistic people patiently waiting for some good or service they urgently desire. The form of a line—narrow and straight and usually reasonably well organized—symbolically communicates order and efficiency. On a map, a line is both the cleanest way to indicate distinctions between territories, as well as the quickest way to get between two points.Footnote ⁵¹ Lines tend to arise in contexts characterized by high degrees of deference to group practices, both in human society (military formations, marching bands) and the insect kingdom (the tendency of ants to form lines epitomizes their highly collectivist behavior [Garnier et al. Reference Garnier, Tucker, Matthew, Edward, Simon and Iain2013]). While people waiting in a diffuse group may have agreed on a relatively functional system of priority—such as quien es ultimo—the sight of a disorganized crowd occupying a space does not clearly indicate that norm to uninformed onlookers (Fernandez Reference Fernandez2013). By contrast, a queue of people or cars provides a tangible indication of generally accepted deference to ordinal priority. At least in the United States, the social meaning of lines is well understood—indeed, internalized—because of the extent to which the practice of queuing is inculcated at an early age. Starting in kindergarten, children are made to form and wait in lines several times per day, and queuing up remains something we do daily—perhaps even multiple times per day—as adults, repeatedly reinforcing the practice and its governing norms. This repetition means that people are primed to believe that most other people are queuing politely, so that we usually follow queue norms without even assessing whether a given line exhibits a high degree of cooperation (Strahilevitz Reference Strahilevitz2003a, 568).

Numerous psychological studies support the theory that lines function as intrinsically powerful symbols of cooperation. First, cooperative behavior tends to spur even more cooperation, resulting in a “reciprocity cascade” (Strahilevitz Reference Strahilevitz2003a, 568). This is in part because the perception of cooperative behavior creates a positive feedback loop, whereby deference to preexisting cooperation validates the behavior of those whose conduct is being imitated. “Imitation is not only the most sincere form of flattery,” Lior Strahilevitz argued, “it also validates and solidifies the behavior of the person who is being imitated” (Strahilevitz Reference Strahilevitz2003a, 568). Lines possess stability, then, not only because their very presence signals cooperation to those outside the line, but also because when people in line see others joining the line politely, they become even more likely to comply with (and enforce) queue norms (Mann 1969). Second, and related, we begin with a default expectation that others behave like us, and since most people are instinctively cooperative, we tend to default to an expectation that others will also comply with social norms. The tendency of waiting lines to embody and even magnify cooperation with applicable norms thus reaffirms the generally held presumption that others tend to follow the rules of the queue (Orbell and Dawes Reference Orbell and Dawes1991).

Lines signal cooperation for another reason that is as much instrumental as symbolic. The presence of people moving along in an organized fashion toward a mutually desired end not only communicates their shared cooperation, but also suggests that waiting in line is an effective strategy for achieving that end. The alternative to an orderly queue is a violent, chaotic mob, which is what often results when line integrity deteriorates.Footnote ⁵² There is no telling whether one will get what one wants in a mob situation; by contrast, queues indicate to potential waiters that if they are patient, things will work out (Malady Reference Malady2013). Finally, it is worth mentioning a final instrumental reason that people may choose to line up even when the payoff of standing in line seems to dwarf the costs of the drudgery of waiting: sometimes lines are not drudgery at all.Footnote ⁵³ On the contrary, they can be fun ways to make friends and participate in a cultural tradition (Mann 1969, 342), and communicate publicly the extent of your interest in a good or devotion to a cause (Brady 2002, 163). Enjoying queuing may not be typical, but it is also not unheard of, and some nontrivial amount of cooperation with line norms may thus be explained simply because people like the experience of waiting in line and have no reason to want to defect.

3. Committed Free-Riders and Efficiently Random Enforcement

The super-salience of lines as signals of widespread cooperation explains their emergence and persistence as means of securing priority when waiting. But accounting for the stability of the queue also requires exploring why it is not undermined by defection. For while most of us tend to follow cooperative social norms unless we perceive significant free riding, a stubborn minority of people will not (Antoci et al. Reference Antoci, Paolo and Luca2009). These are dedicated cheaters who will defect from norms even in the presence of overall cooperation, and they pose a threat to any informal system of order because their noncompliance risks causing those who are only weakly committed to the norm to cheat as well, which may in turn cause neutral and even tolerant reciprocators to defect (Kahan Reference Kahan2003, 9). The result may be the opposite of the kind of norm cascade that causes people to widely adhere to social conventions. This inverse of the norm cascade may be termed a “defection avalanche,” one that upsets the equilibrium of the informal system of order and leads to its collapse (Kahan Reference Kahan2003, 9). If the driver of norm cascades is the general human tendency to cooperate, the driver of defection avalanches is the ubiquitous human desire not to be seen as a sucker—and to abandon the cooperative instinct when others appear to be doing so as well.

However pervasive and seemingly stable the social institution of queuing may seem, it is also vulnerable to defection avalanches. People clearly have an initial inclination to wait in line for service, but if they perceive that others are not doing the same, a once-stable queue may descend into outright chaos. During the 2011 unveiling of the new iPad 2 in Beijing, for example, Apple employees insisted that customers observe the usual practice of lining up in priority order outside the Apple Store in the days and hours before the new devices went on sale. This worked at first, but when a small but visible number of people persistently intruded into the queue ahead of others, all hell broke loose: fights erupted, people rushed the door, and the police had to come in and resolve the situation.Footnote ⁵⁴ Much the same can occur even in higher-queuing cultures. In the United States, orderly lines of people waiting for shopping deals early on Black Friday frequently degenerate into dangerous mobs when stores finally open their doors, sometimes leading unfortunate shoppers to be trampled to death.Footnote ⁵⁵ Even in Great Britain, a country that happily embraces self-effacing myths about queue obsession, politely ordered lines of people waiting for buses will collapse into angry scrums if the doors of an arriving bus do not match up with the location of the front of the line.Footnote ⁵⁶

These examples, while dramatic, remain anomalous—at least in high-queuing societies. Yet no one is obliged by formal law to do so, so why don't dedicated cheaters cut in more often, threatening defection avalanches? Part of the answer is the correlate of lines' capacity to strongly communicate cooperation. Casual observation of a line is unlikely to reveal much defection, even if it does happen, because the overwhelming visual cue of a line is quiet, patient order. What rare defection does take place is unlikely to signal a degree of free riding large enough to cause cooperators to abandon the queue. This is true for three reasons. First, line-cutters are likely to take great care not to be detected, in which case their conduct will not undermine the preexisting sense that everyone is cooperating with line norms.Footnote ⁵⁷ Second, many violations of line norms are ambiguous or hard to enforce. What appears to be a queue jump may simply be someone returning to join his place in line after requesting and receiving permission to leave to use the restroom. Third, line norms are internalized enough that people are unlikely to be vigilantly monitoring queue integrity at all times, so that occasional or marginal rule violations may go undetected entirely. Line-standers probably assume that others share their tendency to wait patiently and not cheat, since, as a general matter, people assume that others share their inclination toward cooperation (Orbell and Dawes Reference Orbell and Dawes1991, 517).

Another reason that lines tend not to descend into defection avalanches lies in the dark side of strong reciprocity: the punitive tendencies of the negative reciprocator. The tendency to punish free-riders even at great personal costs is familiar in life (consider, e.g., the tendency of jilted lovers to seek cruel revenge [Gintis Reference Gintis2000, 177–78]) and well supported by numerous studies (Dohmen et al. Reference Dohmen, Armin, David and Uwe2009, 596). This model aligns neatly with the anecdotal and experimental evidence on queues. Cutting into a line is rude, but exacts only a marginal amount of lost time on people behind the intruder, and no time losses at all on people in front of the intruder. Yet people in line often (though not alwaysFootnote ⁵⁸ ) react aggressively and even violently to cutters, sometimes even engaging in physical altercations to preserve line integrity (Milgram Reference Milgram1986, 685). The possibility of running into these outsized sanctions makes queue jumping a risky and unwise proposition.Footnote ⁵⁹ Saving a few minutes by cutting in line hardly justifies the risk of getting publicly humiliated, punched in the face, or worse, even when discounted by the probability of enforcement.Footnote ⁶⁰

Line sanctions likely work well for a final reason: the proximity and numerosity of possible enforcers. People are less likely to defect when they are in the presence of, or at least observable by, their fellow cooperators (Ostrom Reference Ostrom1998, 6–7). This effect is magnified when possible defectors can be seen by those who might sanction them, and particularly when there are multiple possible people who may exact punishment for norm violation. Queues bear almost all of these features. A would-be line-cutter would have to intrude under the watchful eye of anywhere from a few to hundreds of people, all of whom may well decide to visit severe sanctions for flouting queue norms (Bateson Reference Bateson2006). This combination of physical scrutiny by and numerosity of potential punishers contributes to the disproportionate costs borne by anyone who seeks to cut in, and further diminishes the likelihood of defection. Finally, the numerosity of people in lines promises the possibility of group sanctions against norm violators. As Mann found, those in a queue may join together to shame or sanction a line-cutter (Mann 1969, 347), sharing the burdens of enforcement in a way likely to lower their costs while increasing the intensity of the deterrent to the defector (Boyd et al. Reference Boyd, Herbert and Samuel2010).

This section has explained the spontaneous order of lines in research showing that humans tend to be strong reciprocators rather than entirely selfish rational utility maximizers. Positive reciprocation (the tendency to follow along with perceived cooperative behavior) explains why people reflexively line up and wait for services, while negative reciprocation (the tendency to sanction only perceived violations of cooperative behavior) explains why line cutting is relatively rare and does not trigger defection avalanches. This account illuminates an underexplored corner of the law and norms literature: the phenomenon of emergent order among loose-knit groups. Traditional explanations, such as fear of social sanctions or desire for group esteem or future cooperation, may work for close-knit groups but cannot fully account for why queues emerge. At the very least, strong reciprocity provides an explanation of norms in the understudied loose-knit group. This could mean that close- and loose-knit groups require different theories of norm compliance (Strahilevitz Reference Strahilevitz2003b), but an alternate, more ambitious version of this thesis is that strong reciprocity explains norms in both kinds of groups. The theory that people comply with extralegal rules because of an innate tendency to reciprocate with known forms of social cooperation (and to strongly sanction the few outliers who defect) may explain norm compliance just as well, if not better, among those who are acquainted as it does among strangers. Whether this account provides the best account for norm compliance in close-knit groups is a deep question that lies beyond the scope of this article, but it is well worth at least noting the plausible conjecture that strong reciprocity could be not just a framework explaining why spontaneous order emerges in loose-knit groups, but a grand unified theory of social norms.