In which scenario can an officer make a warrantless arrest for refusing to remove a substance thrown on the public way?

A warrantless arrest can occur under certain circumstances defined by law, particularly when there is a violation of law happening in the officer's presence. In this case, if an officer is present and observes an individual committing an offense — such as throwing a substance onto a public way and subsequently refusing to identify themselves — the officer is justified in making an arrest. This aligns with the legal principle that allows law enforcement to act without a warrant in instances where a crime is being directly witnessed.

The requirement for the officer to be in presence of the offense is crucial; it establishes legal grounds for immediate action without needing to first secure a warrant. The refusal to identify oneself can further complicate the situation, potentially indicating a desire to evade involvement with law enforcement procedures.

In contrast, the other scenarios do not provide clear legal grounds for a warrantless arrest. If the substance is harmless, there is generally no offense to arrest someone for. The specificity regarding the size of the substance does not inherently provide cause for arrest without additional context of criminal activity. Prior knowledge of a suspect, while possibly useful, does not justify a warrantless arrest unless the officer simultaneously witnesses a current offense. This emphasizes the importance of both the officer’s presence at the scene of the crime and the immediate