"'obviously that is a legitimate police function'"

Executing old warrants -- no matter how minor -- is legal.  But legal experts say the tactic becomes illegal if it is done solely to investigate political activity.

The half-dozen or so stories  fit a pattern: each individual was approached and questioned by officers who said they were picking up people on arrest warrants for low-level, non-criminal violations, such as public urination, walking around with an open container of alcohol or biking on a sidewalk. These warrants can stay open for years.

Court officials say there are more than 1 million bench warrants currently open for these types of violations in New York City.  But this week, squads of police officers decided to act on a few of them.

Read More | "Using NYPD Warrant Squads to Monitor Protesters May Violate Constitution: Experts" | Alisa Chang | ?WNYC