It doesn't defy police. It says they don't consent to being searchd. Not giving consent isn't "defiance".
This shirt is being sold in a far left publication that routinely portrays Bush as a vampire, as a Nazi, etc.
The maker of the shirt is an activist for illegal immigrants.
People who will be buying and wearing this shirt are being defiant of the searches. They are the same people who make New York and America less safe by being pro-illegal, anti-gun, anti-profiling.
At some point, the f-you attitude will boil over and the real culprits will be targeted. However, this may take another generation or so - we should probably give the phony WOT a chance. That way, there won't be much disagreement when more dramatic war measures are implemented in the correct overseas targets.