Law Society of Ontario (LSO) Paralegal Practice Exam 2025 - Free Paralegal Practice Questions and Study Guide

An officer can arrest a person without a warrant when they find someone actually committing a criminal offense. This is a fundamental principle of law enforcement, known as a "citizen's arrest" or "felony arrest," which allows officers to act immediately to prevent further harm, protect public safety, and maintain order. The immediacy of the situation often justifies the lack of a warrant since waiting for a warrant could result in evidence destruction, escape, or further criminal activity.

The requirement here is based on the officer's direct observation of a crime in progress, which provides the necessary grounds for the arrest. This ensures that law enforcement can respond swiftly to potential threats or violations, upholding the law and protecting the rights of the community as a whole.

Other scenarios where officers act, like having a signed statement from a witness or suspecting someone might commit a minor offense, do not provide the same immediate justification for a warrantless arrest. The legal framework emphasizes the importance of direct evidence of a crime being committed as the appropriate threshold for such an action.