Under which conditions can a police officer arrest a person without a warrant?

A police officer can arrest a person without a warrant if they have reasonable grounds to suspect that the individual is committing or has committed an offense. This is a core principle in law enforcement, aimed at empowering police to act swiftly to prevent further criminal activities or to address ongoing offenses.

The criteria of "reasonable grounds" is crucial here; it ensures that the officer’s suspicions are based on factual information and evidence rather than mere conjecture or personal bias. This provision allows officers to fulfill their duty to maintain public safety and order effectively, particularly in situations where delaying an arrest could lead to harm or the escape of a suspect.

The other options do not align with the typical legal standards for immediate arrest. For instance, while suspecting someone is injured does not provide a basis for arrest, being authorized by a superior officer may inform actions taken but does not constitute a direct ground for arrest without a warrant. Additionally, having a personal vendetta against someone starkly contradicts the principles of fair and just law enforcement and cannot serve as a legal basis for an arrest. Such actions would be deemed unprofessional and abusive of power.