The American Civil Liberties Union of Minnesota offered a $1,000 reward Monday to anyone who can prove a case in which someone in the state has been charged or convicted of impersonating a voter.

State ACLU Executive Director Charles Samuelson said his organization put up the bounty to show a Republican-proposed constitutional amendment to require voters to show photo identification at the polls is not needed.

Samuelson said ACLU attorneys have not been able to find a single case of voter impersonation in the past 10 years.

“If you can’t find a crime, why change the law?” he asked at a Capitol news conference where he stood behind a stack of 1,000 $1 bills.

In response, the voter ID bill’s sponsor, Rep. Mary Kiffmeyer, R-Big Lake, noted the U.S. Supreme Court has found that “voter impersonation is incredibly hard to detect and is nearly impossible to prosecute, yet it has said we know for a fact that it occurs.”

In Minnesota?

“Of course,” Kiffmeyer said.

Anyone who wants to take the ACLU up on its challenge, which covers the past 10 years, can mail the evidence along with contact information to the ACLU office at 2300 Myrtle Ave., Suite 180, St. Paul, MN 55114.

The deadline for submitting evidence is March 30. The ACLU will announce the results April 5.

Bill Salisbury can be reached at 651-228-5538.