What constitutes a lawful arrest without a warrant?

A lawful arrest without a warrant in New South Wales is justified when an officer apprehends someone who is committing an offense in their presence or for a serious crime. This provision is rooted in the understanding that immediate action is necessary to prevent further criminal activity or to ensure public safety.

When an officer directly witnesses a crime, it provides immediate grounds for arrest, as it ensures that the police can effectively respond to offenses as they occur. Additionally, serious crimes, which may include offenses such as violent acts, theft, or drug trafficking, allow for immediate arrest without delay, facilitating the enforcement of law and order.

The other choices do not meet the criteria for a lawful arrest without a warrant. For instance, arrests based solely on suspicious behavior do not provide sufficient grounds without an observable offense. Similarly, conducting thorough investigations before an arrest or relying solely on routine checks without observed criminal conduct do not comply with the immediate need for a warrantless arrest.