From 1967 onwards, the maritime powers revived their campaign against other states’ expanding claims to coastal waters, this time nudged along by a new member of the club: the USSR. Their greatest concern at this time was not the twelve-mile territorial sea limit, which they now deemed acceptable, nor fisheries, which took second place to strategic concerns, but rather the overlapping of straits by newly extended territorial seas. At the United Nations law of the sea conference of 1973–1982, they rejected the unsuspendable innocent passage regime set out in the Corfu Channel decision and the 1958 territorial sea convention, and agitated instead for ‘transit passage’ through straits. This regime, delinked from the idea of innocent passage, upheld freedom of navigation and overflight in straits used for international navigation, and confirmed that submarines were permitted to transit straits submerged. The straits states, wishing to retain some control over adjacent waters, managed to claw back one concession relating to enforcement if a vessel was ‘causing or threatening major damage to the marine environment of the straits’.

When the conference delegates turned their attention to seabed mining, many proclaimed the great importance of the issue – from either a positive or negative perspective – declaring that it would underwrite a new international economic order, or present a fundamental threat to land-based mining industries, or exemplify the virtues of the free market. The problem was that no state knew how profitable seabed exploitation might be, or the technological challenges involved, or its potential effect on commodities markets. Because of this uncertainty, none of them wanted to put themselves at a potential disadvantage or forego future rewards, so the negotiations were particularly hard fought and protracted. One casualty would be the common heritage concept, replaced with the parallel system by the G5 powers, and with technology transfer by the G77 countries. Another casualty was the cooperation between the industrial powers, with some proposing anti-monopoly clauses and production quotas to protect their own mining concerns and constrain competitors. The outcome managed to displease every state, but most eventually signed the convention with the agreed seabed provisions in 1982.

Throughout the post-war decades, archipelagic states such as Indonesia and the Philippines, given impetus by the Fisheries decision, stressed the organic relationship between land and sea within an archipelago – an approach in marked contrast to the existing law’s terrestrial orientation. This relationship was presented as grounds for specific claims to archipelagic waters enclosed within straight baselines. The concept was subject to various challenges: from outright opponents who resented archipelagic encroachments on the high seas and the seabed; from continental states with outlying archipelagos who wished to claim the same rights as mid-ocean archipelagos; and from the maritime powers, who wished to safeguard unimpeded passage through other states’ archipelagic waters. In the event, the United States made recognition of the concept conditional on the acceptance of archipelagic sea lanes, within which transiting vessels would enjoy extensive rights unfettered by archipelagic state control.

The tumultuous early years of the 1973–1982 conference placed enormous strains on both the developing countries and the maritime powers. The ‘group of seventy-seven’ managed to secure recognition of the 200-mile exclusive economic zone and a consent regime for marine scientific research. But the divisions within the group, along with the pressures exerted on it by the powers, meant that they achieved less than they had originally hoped for, with the coastal states losing out to the powers over military activities in the exclusive economic zone, and the landlocked and geographically disadvantaged states losing out to the coastal states over guaranteed access to fishing surpluses. By contrast, the powers’ ‘group of five’ made a strong start to the conference, securing their navigational interests in the territorial sea, then in straits, and then in archipelagos and the exclusive economic zone. Consensus worked in their favour, allowing them, as a minority, to prevail over the majority. But having secured their initial objectives, their incentive to continue cooperating with each other would be weakened as they entered the final stretch of the conference.