The facts say this: African-Americans make up 10 percent of the House, but as of the end of February, five of the sitting six named lawmakers under review by the House Ethics Committee are black. The pattern isn't new. At one point in late 2009, seven lawmakers were known to be involved in formal House ethics inquiries; all were members of the Congressional Black Caucus. An eighth caucus member, Rep. Jesse Jackson Jr. of Illinois, had also been under investigation, but his probe was halted temporarily while the Justice Department undertook an inquiry of its own.This isn't too surprising given the existance of congressional districtsdesigned to ensure most voters are black. Most black representitives do not have to worry about appealing to non-black voters- this encourages politicians to play the race card to succeed and when elections become a matter of ethnic identity rather than competence or integrity- more corrupt individuals thrive.
All told, about one-third of sitting black lawmakers have been named in an ethics probe during their careers, according to a National Journal review.
This can be thought of as the Clay Davis effect:
It is also one reason why ethnically divided countries without a single demos tend to be more corrupt as voters take the attitude that they need a bigger crook representing them than their neighbours.