"if a police officer has a reasonable belief that someone is committing or about to commit a crime, that officer can stop the suspect "

I believe the answer is: without getting a warrant

For example, we can see this in the situation when police officers heard gunshots fired from inside an apartment.
In this case, the Police officers would have the right to barge into the apartment without a warrant in order to prevent the perpetrator from escaping or prevent potential death.

Afederal parliamentary republic is  unlimited.