I feel honoured to be your guest here, and am pleased to have this opportunity to lecture on my academic passion—“The Formal Character of Law”. Law has several fundamental characteristics. My main thesis is that formality is one of these. I define a “formal” feature of law as one that is in some way independent of the substantive content of the law. For example, the definitiveness of a legal rule is a formal feature of the rule's configuration, and is independent of the substantive content of the rule. Formal configuration is one thing, and substantive content another. But as we will see, there are different ways in which a formal feature may be independent of substantive content, and there are still other, related, senses of formal.

This article is a study of judicial attitudes to exclusion clauses in contracts for the sale of land. It examines the various devices which the courts have developed in order to limit the effect of such clauses and suggests that one of these devices has emerged as paramount: the principle that a vendor may, in appropriate circumstances, be estopped from relying on a condition by reason of his knowledge or conduct. One form of this estoppel will be shown to be of particular importance. This is the “well-established rule of equity” that a vendor of land cannot rely on a condition of sale, framed in general terms, to cover a specific encumbrance or other defect in title of which the vendor knew or ought to have known, and which he failed to disclose to the purchaser prior to contracting. The culmination of the article is a study of the rationale and precise manner of operation of this rule-which for convenience will be called the “no-disclosure, no-reliance” rule.

Defendants to criminal or civil proceedings will often seek to escape liability by showing that a public authority has acted ultra vires. For example, a person prosecuted for infringing a byelaw or breaking a licence condition may seek to advance the defence that the byelaw or condition is ultra vires the public authority which made or imposed it. Again, a person sued in debt by a public authority may seek to raise the defence that no money is due because the authority acted ultra vires in imposing the charge which it is now suing to recover. Nowadays, too, the European Court of Justice may hold in effect that an Act of Parliament is contrary to Community law and so should not be applied by UK courts. A person prosecuted, say in a magistrates' court, for a criminal offence created by a statute which is or may be contrary to Community law may seek to persuade the justices to “disapply” the statute—virtually, in the case of a post-Accession statute, to treat it as ultra vires the UK Parliament—and so to acquit him.