New York City police were collecting information about the political leanings of protesters they arrest. They have now stopped this horrendous practice:

New York City police this week ended a practice of questioning arrested anti-war demonstrators about their political affiliations and are destroying a database containing the information, officials said Thursday.

Police Commissioner Ray Kelly said he had been unaware of the practice but that it was stopped after civil libertarians complained that it violated the Constitution

I agree with the civil liberatarians. Political affiliation has nothing to do with the reason for the arrest and is not pertinent to the case. Besides, who has to ask about the politics of an anti-war protester, we all know they're Baath Party.