AUGUSTA — Secretary of State Matthew Dunlap won’t appeal a judge’s ruling overturning his decision to invalidate a marijuana legalization referendum, potentially clearing it for the November ballot.

His office will now review thousands of signatures that it threw out in March, and a top proponent said “we’re confident that we collected far more valid signatures of Maine voters than are required to qualify for the ballot.”

Superior Court Justice Michaela Murphy overruled Dunlap on Friday, finding that he “committed an error of law” by invalidating the question in March largely because he found that the signature of a notary — Stavros Mendros, president of Olympic Consulting in Lewiston — didn’t match a signature on file with Dunlap’s office.

Referendum proponents, led by the national Marijuana Policy Project, submitted 99,000 signatures to the state in February, well over the minimum of 61,123 valid signatures needed. But Dunlap threw out nearly half for a variety of problems, and proponents appealed.

Their case centered on 17,000 of those signatures notarized by Mendros, a controversial figure who was also at the center of a failed York County casino question that was invalidated this year by Dunlap in a decision upheld by Murphy after a separate appeal.

Dunlap tossed all those signatures, saying Mendros’ signature was inconsistent and didn’t match the one on file with the state.

But a lawyer for proponents said Dunlap used his authority in an overly broad way and lacked evidence. Murphy agreed, saying in a 26-page ruling that Dunlap’s ruling placed too much burden on the referendum’s proponents.

In a statement issued late Wednesday afternoon, Dunlap said his decision not to appeal was “grounded entirely in the goal of this office to insure that initiative questions that appear on the ballot carry with them the public integrity of a legitimate effort.”

Now, he said his office will conduct a further review of invalidated signatures in the effort to see if it qualifies for the statewide ballot and issue a new determination “as expeditiously as possible.”

“We’re glad the secretary of state will be reviewing the petitions,” said David Boyer, Maine political director for the Marijuana Policy Project, “and we’re confident that we collected far more valid signatures of Maine voters than are required to qualify for the ballot.”