I just found this great Citizen’s Guide to Refusing New York Subway Searches at FlexYourRights.org. They have all kinds of info about surviving encounters with law enforcement with your rights intact.
1. When Refusing a Search, Be Cool
2. Refusal is Not Guilt
3. Shut Your Mouth and Your Wallet
4. Do Not Physically Resist
5. WARNING: DO NOT RUN!
6. Report Abuses
7. Spread the Word!