PORTLAND — The Oregon Supreme Court on Thursday ordered a rewrite of the ballot title for an initiative petition that seeks to enact term limits for state lawmakers.

Ballot titles are intended to provide a concise, neutral description of a measure. They're regarded as crucial information for voters who haven't done homework on an issue, and the language is frequently challenged in court.

The ballot title certified by Attorney General Ellen Rosenblum this summer accurately says the measure would prohibit state legislators from serving more than eight years during any 12-year period.

But Oregon's high court agreed with an opponent of the ballot title that it omits a piece of key information: The measure would apply retroactively, quickly changing the composition of the Legislature.

The opinion written by Justice Martha Walters said there are instances when a measure is complex and some details can't be included in the brief description. But, she added, the caption must accurately identify the major effects of a measure in terms that won't confuse voters, and the term-limits title fails in that regard.

"Without further information, voters reasonably could think that the measure is prospective only; that is, only legislative service after the effective date of the measure will affect a legislator's continued service."

The initiative petition was filed by former Republican gubernatorial candidate Bud Pierce. To qualify for the November 2018 election, supporters must collect nearly 90,000 signatures from registered voters.

The rewrite was sought by Matt Swanson, executive director of the Oregon chapter of Service Employees International Union.

Oregon voters overwhelmingly approved term limits for state legislators in 1992, but the state Supreme Court reversed their decision a decade later on technical grounds. The governor, state treasurer and secretary of state are subject to term limits.