A more thorough explanation:

Definition: Hilary Rules were a set of English pleading rules that aimed to ease the strict pleading requirements of the special-pleading system. These rules limited the scope of the general issue in the formed actions and forced the defendant to set up affirmatively all matters other than a denial of the breach of duty or of the wrongful act.

The Hilary Rules were introduced in England in the 1834 Hilary Term, following an 1828 initiative to examine procedural laws and other subjects and to report to Parliament changes that might be enacted. However, the rules had the unintended effect of extending the reach of strict-pleading requirements into new areas of law. This led to widespread dissatisfaction with the Hilary Rules, which were later liberalized under the 1873–1875 Judicature Acts.

Example: Under the Hilary Rules, if a plaintiff sued a defendant for breach of contract, the defendant was required to plead specifically to each allegation made by the plaintiff. For instance, if the plaintiff alleged that the defendant failed to deliver goods on time, the defendant had to admit or deny that allegation. If the defendant denied the allegation, they had to provide a specific reason for the denial.

This example illustrates how the Hilary Rules limited the scope of the general issue in the formed actions and forced the defendant to set up affirmatively all matters other than a denial of the breach of duty or of the wrongful act.