The petitions were rejected because all the rules established by the Legislature for those collecting the signatures were not followed. The measures were bankrolled by Las Vegas Sands Corp. Chairman Sheldon Adelson.

Two would divert room taxes from the convention authority to state programs and public education and the third would require a two-thirds vote on ballot measures that would raise taxes.

Lee Rowland, an attorney representing the ACLU of Nevada, said the source or content of the petitions is irrelevant.

The issue of importance to the ACLU is the process, and access to the ballot by citizens, not the subject matter of the measures, she said.

In this case, tens of thousands of signatures are being discounted because of procedural issues.

"Fundamental fairness was lacking here," Rowland said.

The request to file the brief was submitted to the court on Wednesday. The court must now decide whether to accept the brief.

Secretary of State Ross Miller refused to approve the measures for the ballot despite their receiving double the number of signatures needed to qualify.

Miller said rules adopted by the 2007 Legislature regarding affidavits submitted by petition gatherers were not followed.

A Carson City judge agreed. The case is now before the Supreme Court.

But Rowland said in the brief that the petitioners, including former state Treasurer Bob Seale and former state Controller Steve Martin, relied in good faith on Miller's Web site in following the rules for petitions.

The Web site had not yet reflected the changes made by the Legislature when the signature gathering efforts were launched.

The new rules adopted by the Legislature were intended to prevent fraud. But the ACLU brief states there is no evidence that any of the signatures were fraudulently obtained.

"Overly burdensome ballot access laws, usually designed to trap the unwary and favor the politically connected, violate the First Amendment right of voters to express their political beliefs by voting for proposed legislative measures of their choice," the brief states.

The request to file the brief came on the same day that attorney Scott Scherer, representing Seale and Martin, filed a brief requesting that the court overrule the district court.

The Supreme Court has put the case on a fast track because of the fast-approaching November general election. The case is scheduled to be heard Aug. 20.

Scherer said the lower court had erred with the wholesale striking of more than 350,000 signatures contained in the three petitions by focusing only on technical deficiencies.

Scherer also argued that the Legislature had no basis for imposing the additional requirements on petition supporters, calling the rules an unconstitutional infringement on their First Amendment rights.