In 1815 the Woodrop-Sims, a sizeable American ship inbound to London, hit and sank the Industry, a much smaller vessel, in the English Channel. Litigation followed. In a two-page judgment (1815) 2 Dods 83 Sir William Scott held her liable, at the same time providing a beguiling distillation of the then law of maritime collision. The whole thing, he said, reduced to four easy theses. If your damage was all your fault you got nothing: if it was the other ship’s fault, it had to make reparation. If both of you were at fault, you got half your losses: if neither could be blamed, the law had nothing to say about the matter.

Times, of course, have changed. Up to a point, however, the law on the subject retains a good deal of its 19th century elegance and transparency. English and American authority cross-fertilize to an extent unusual elsewhere, exposing a remarkable substratum of common principle. England, indeed, still retains the idea, astonishing for the late 20th century, of a single “admiralty judge” and a remarkably small camaraderie of lawyers practising before him. And even in the United States, home of litigation fever, juridical diversity and burgeoning inconsistent case law, collision cases remain to a surprising extent neatly homogenized. No doubt this is largely because Admiralty law is in practice a federal monopoly, consistently immune to jury trial, and—it must be remembered—one of the few areas where the Supreme Court still concerns itself with commercial disputes.

But, of course, such a state of 19th century innocence could not last. The cause is not hard to see, even laying aside the 13 co-ordinate but quarrelsome federal Courts of Appeals whose existence so enlivens the study of American law for the outside reader. Just consider the spawning of rules and sub-rules about practice and evidence, the casuism and scholasticism surrounding the interpretation of the Collision Regulations, and the complexity of limitation of liability and pollution regimes: plus, of course, the engaging diversity of treaties aimed at unifying the law the world over. No doubt this explains why Professors Healy and Sweeney’s perceptive new book on American collision law, appearing about the same time as the new Marsden in England, weighs in at some 600 pages. In this space, however, it manages to tease order from chaos; to put in manageable compass the principles that matter; and, even better, to criticize some of the more foolish ones and say what ought to be done about them. The authors start with “basic principles”: history, choice of law, the difference between liability in rem and in personam; and (vital in the American context) what counts as an Admiralty case, allowing as of right the invocation of federal jurisdiction and the abjuration of jury trial. Chapter 2 deals with evidence, a somewhat specialized topic in the US and worth extended treatment, if only because until about 20 years ago courts sitting in admiralty were, literally, a law unto themselves, not being bound by the rules obtaining elsewhere in the federal courts. Noteworthy here is the extensive, and pretty devastating, criticism of the “Pennsylvania rule”—a bizarre principle, now virtually unique to the US, whereby if a vessel is in breach of any statutory regulation whatever, not only fault but causation is presumed against her in the event of any accident. Five chapters ensue on the detail of the Collision Regulations, followed by individual coverage of pilotage (in which, English readers will remember, the defence of compulsory pilotage remains in force in the US, tug and tow, pollution, both-to-blame, damages, limitation, salvage and insurance. The usual appendices are there, covering everything from the up-to-date text of the Collision Regulations to a number of international treaties and even the American Institute Hull Clauses.