A plan to ask voters to limit state legislators to eight years in office does not meet constitutional muster, an appeals court ruled today.

The 1st District Appellate Court unanimously held that the constitutional change championed by GOP gubernatorial candidate Bruce Rauner is neither a “structural” nor “procedural” change as required by the state constitution.

In a 15-page opinion authored by Justice Maureen E. Connors, the court said the group pushing term limits “failed to adequately distinguish” the plan from a similar one rejected by the Illinois Supreme Court in the 1990s.

“We are bound by our [S]upreme [C]ourt’s holding — sparse as its reasoning was — that term limits involve ‘the eligibility or qualifications of an individual legislator,’ and so are neither structural nor procedural,” Connors wrote.

Backed by Rauner, the Committee for Legislative Reform and Term Limits argued that the plan’s other components — changing the size of the House and Senate and increasing the threshold number of votes to override a governor’s veto — worked in conjunction with the term limits idea to change the composition of the legislature.

The proposal, which the committee seeks to place on the November ballot, also would necessitate that members of the Senate serve four-year terms instead of staggered terms of both two and four years.

The committee argued that would be a constitutional change to the procedure of electing senators and the structure of the Senate by altering its seniority system.

But the court was not convinced by that argument, either.

“The [c]ommittee seems to assert that term limits are intertwined with the proposal to make all Senate terms four years,” Connors wrote.

“Yet, while four-year Senate terms would facilitate the eight-year term limits, they do not change term limits’ fundamental quality — as stated by our [S]upreme [C]ourt — of only relating to the eligibility or qualifications of an individual legislator.”

The three-judge panel, which also included Justices Thomas E. Hoffman and Terrence J. Lavin, also said the plan violated the free and equal clause because the plan is “extremely broad,” and several of the other components could stand as independent provisions.

The decision affirmed a ruling by Cook County Circuit Judge Mary L. Mikva.

The committee is expected to ask the Illinois Supreme Court to review the case.

The deadline for a measure to get on the ballot is technically Friday.

J. Timothy Eaton, a partner at Taft, Stettinius & Hollister LLP, is representing the Committee for Legislative Reform and Term Limits.

Michael J. Kasper, a partner at Fletcher, O'Brien, Kasper & Nottage P.C., is representing a group of nonprofits and other citizens who are challenging the proposal.