D.C. mayoral candidate Linda Cropp’s campaign paid petitioners $1 for every signature they collected to get her name on the ballot, a practice that landed current Mayor Anthony Williams in trouble four years ago.

Paying signature-gatherers by the amount of names they collect is legal in D.C., but election watchdogs argue that it encourages fraud and many states ban the practice. Williams was fined more than $250,000 in 2002 because many of the signatures he paid for turned out to be fake.