In concert with recent pessimistic scholarship on the human rights regime, Eric Posner slams the efficacy of international human rights law in The Twilight of Human Rights Law. He argues that international law has done little if anything to improve human rights on the ground, and insists that to maintain otherwise is to ignore the empirical evidence.

Beginning with a brief history of international human rights law, Posner reminds us that the purpose of establishing a formal human rights legal regime was to improve human rights in the immediate aftermath of World War II. He surveys all the regime's various components, including the eight core human rights treaties (with their accompanying state-compliance review committees) and the appurtenant human rights mechanisms (including courts, national human rights institutions, and the Universal Periodic Review). He then offers reasons why states might adhere to international human rights law—for instance, to ensure international aid or to avoid being sued by their citizens. The motives, then, are instrumental, and it is no surprise that states often find ways to flout the rules they formally agree to.

Posner cites several studies that demonstrate empirically how international law has failed to materialize human rights on the ground. He cites a study published by Freedom House in 2013 on international human rights treaty compliance that concludes that some authoritarian regimes actually engaged in more human rights violations after they had ratified human rights treaties; and another study by Freedom House that suggests that countries do not consistently restrict aid to human rights-violating states. And, although he admits some notable successes for the international human rights regime, as in its role in ending apartheid in South Africa, Posner emphasizes what the evidence empathically forces him to conclude: that “human rights treaties do not systematically improve human rights outcomes.”

As a better means of advancing people's wellbeing, Posner encourages thinking of human rights as a development issue, not a legal one. He considers donor countries helping to build infrastructure in aid countries as having more impact than forcing a country, for instance, to abolish torture. Not only would building roads boost economic growth but it would also improve access to voting stations, potentially advancing political rights as well.