From a Fox News story headlined "Ex-Official Accuses Justice Department of Racial Bias in Black Panther Case" (You'll recall this incident -- see the video below.)
The Bush Justice Department filed a civil suit against the Black Panthers and won a judgment. After Obama won the election, a whistleblower testified that they were told not to pursue cases with black defendants and white victims. The Obama administration, according to the Fox story, "moved to dismiss the charges the following month after getting one of the New Black Panther members to agree to not carry a "deadly weapon" near a polling place until 2012."
That is, not until the tactic is useful again.