U.S. Sen. Jim Webb is calling on District of Columbia Mayor Vincent Gray to review a media report that city police are putting drivers in jail for having expired tags.

The Virginia Democrat says in the letter sent Thursday that there is "absolutely no justification" for incarcerating citizens whose only offense is an expired tag. Earlier this week, Fox News reported accounts of D.C. police arresting drivers for registration violations.

Police spokeswoman Gwendolyn Crump told The Associated Press early Friday that officers are sworn to enforce laws that are on the books. She says the city allows for a grace period and many officers use further discretion.

Crump says concerns with the law should be addressed with city legislators.