WASHINGTON

Albert W. Florence believes that black men who drive nice cars in New Jersey run a risk of being questioned by the police. For that reason, he kept handy a 2003 document showing he had paid a court-imposed fine stemming from a traffic offense, just in case.

It did not seem to help.

In March 2005, Mr. Florence was in the passenger seat of his BMW when a state trooper pulled it over for speeding. His wife, April, was driving. His 4-year-old son, Shamar, was in the back.

The trooper ran a records search, and he found an outstanding warrant based on the supposedly unpaid fine. Mr. Florence showed the trooper the document, but he was arrested anyway.

A failure to pay a fine is not a crime. It is, rather, what New Jersey law calls a nonindictable offense. Mr. Florence was nonetheless held for eight days in two counties on a charge of civil contempt before matters were sorted out.