Say the ratio out loud before you open Reasoning — recalling it unprompted is exactly what the exam pays for.
Why it matters
It is the case that killed the old rule that a foreign judgment is mere evidence, re-examinable on the merits, and it pushes conclusiveness to its logical extreme. If you can state this case you can state what conclusiveness really costs.
Facts
A French court, misconstruing an English penalty clause, fixed damages at the exact amount of the freight. When enforcement was sought in England the defendant pleaded that mistake — a mistake about English law made by a French judge.
Held
The plea was rejected. A foreign judgment of a competent court cannot be reopened in England on the merits, and the English court is not entitled to investigate the propriety of the proceedings in the foreign court. There can be no difference between a mistake as to English law and any other mistake.
Reasoning
Step one — the basis of enforcement is obligation, not review. On the doctrine of obligation in Williams v. Jones, once a court of competent jurisdiction has adjudged a sum to be due, a legal obligation to pay it arises. The English court enforces that obligation; it does not sit in appeal.
Step two — a mistake is not a ground that negatives the obligation. The recognised defences are want of jurisdiction, fraud, public policy and breach of natural justice. Error is not among them.
Step three — accept the consequence candidly. An English court may be compelled to enforce a foreign judgment based on a complete error of English law. That is the price of conclusiveness, and the course states it in terms.
Exam use
It opens: Is a foreign judgment conclusive on the merits? — and it is the case that answers yes, in the strongest form.
Then give the Indian contrast, which is the examinable difference. English law does not permit re-examination on the merits at all. India does, but only to the limited extent of s. 13(b): a decree passed without recording any evidence is not a judgment on the merits (Babu Nemi Chand v. Y.V. Rao); a judgment given after the defence was struck out for failure to answer interrogatories is not on the merits (D.T. Kaymer v. P. Viswanathan); but the inquiry is confined — the Indian court is not to decide whether the foreign decision was right, only to see that the foreign court applied its mind to the facts and the law (Mallappa Yellappa v. Raghavendra).
Note the historical loose end. The rule against merger — that a creditor with a foreign judgment may sue on the judgment or on the original debt — survived the death of its rationale in this case, and was called an illogical survival of precarious existence in Carl Zeiss v. Rayner & Keeler.
It does not decide that fraud, want of jurisdiction or a breach of natural justice may not be pleaded; those defences are untouched.