PORTLAND, Maine — The Augusta lawyer who is challenging Maine’s Sex Offender Registry law will receive the Maine Civil Liberties Union’s annual prize next month.

James E. Mitchell, 67, who lives in Vassalboro, will be honored at the annual Scolnik Dinner to be held on Wednesday, May 6, at the Harraseeket Inn in Freeport. The dinner is named for MCLU founder Louis Scolnik, who practiced law in Lewiston for many years and served on the Maine Supreme Judicial Court from 1983 to 1988. Now 86, Scolnik lives in Andover, Mass.

The award is given each year to honor a Maine lawyer who has made an outstanding contribution to the cause of civil liberties, according to an MCLU press release.

Mitchell has been probate judge of Kennebec County since 1979. He is married to Maine Senate President Elizabeth “Libby” Mitchell, D-Vassalboro.

He said last week he is “very honored to be singled out for the award.”

On Good Friday 2006, Mitchell filed a lawsuit challenging the constitutionality of the Maine Sex Offender Registry. Two days later two men who were listed on the registry were murdered by a 20-year-old Canadian man who committed suicide less than 24 hours after the killings. Neither of the men was Mitchell’s client.

Mitchell won a major victory last year when the Maine Supreme Judicial Court ruled that his client — who was unnamed, identified only as “John Doe” — was entitled to a jury trial in his challenge of the law. Since then, Mitchell has taken on 15 other clients who are required to register as sex offenders. Other lawyers around the state also have pending cases.

The Legislature also is considering changes to the registry in the aftermath of the murders three years ago.

Mitchell was born in Little Rock, Ark. He graduated from Princeton University in 1964 and earned a law degree from Yale University in 1971.

He came to Maine in 1973 to serve as the director of the Maine State Housing Authority in Gov. Kenneth Curtis’ administration. He left government two years later to go into private practice.

Mitchell is a member of the bar in Arkansas, Connecticut, Maine and several federal courts, including the one in Maine. He is the author of “Maine Probate Manual,” Tower Publishing Co., 1981, now published as “Maine Probate Procedure” by Batterworths.

“Throughout his legal career, Mitchell has shown a strong commitment to the defense of civil liberties, taking on such cases as a class action lawsuit against the U.S. Immigration and Naturalization service in Bangkok on behalf of Vietnamese refugees in Thailand,” said Shenna Bellows, MCLU’s executive director.

The newly elected president of the American Civil Liberties Union will speak at the dinner. Susan Herman, a Centennial Professor of Law at Brooklyn Law School, was elected in October to the ACLU’s top leadership post.