A study that suggests black motorists are more likely to speed than whites is another attempt to vindicate New Jersey state troopers who practice racial profiling, the head of the state's NAACP chapter said Wednesday.

The Rev. William Rutherford said he had not read the study but didn't believe its findings.

"We're only 12 percent of the population. If you arrested every white person that was speeding and every black person that was speeding, common sense will tell you that you're going to arrest more whites than blacks," Rutherford said.

The Justice Department questioned the methods used to gather the data for the study, released Tuesday by the state attorney general's office after state officials initially refused to make the results public.

Specially designed radar gun cameras were used last spring to photograph tens of thousands of drivers on the New Jersey Turnpike as part of the study. The photos were shown to teams of three evaluators who tried to determine each driver's race without knowing whether they were speeding.

The study's author, James Lange, has stood by the methodology and said most concerns about the report are unfounded or have been addressed.

The study found black drivers sped much more than other drivers, and the racial gap was wider than officials expected. The racial gap widened at higher speed limits, but there was little difference in 55 mph zones, the study also found.

A spokeswoman for the Justice Department did not immediately return a telephone message seeking comment Wednesday.

A 1998 shooting of four minority men by state troopers on the turnpike inflamed accusations that state police targeted minority motorists for searches. A year after the shooting, state officials admitted troopers practiced racial profiling.