Irregularity

In practice

The doing or not doing that, in the conduct of a suit at law, which, conformably with the practice of the court, ought or ought not to be done.

115 111. 590.

It is the technical term for every defect in proceedings or the mode of conducting an action or defense. It is a comprehensive term, including all formal objections to matters of practice. An irregularity is a formal but a nullity is a substantial defect. One applies chiefly to the manner, the other to the matter or merits of the proceeding; the for met is voidable, the latter absolutely void. As a general rule whenever there is any doubt upon the matter it will always be safer to treat the defect as an irregularity rather than as a nullity.

130 111. App. 588; Macnamara on Nullities and Irregularities in Law, 20.