Both the LDS Church and the Utah Pride Center have filed legal briefs in the cases.
In Salt Lake City, gay civil rights advocates will hold a candlelight vigil Monday at 6 p.m. in the Salt Lake City Library amphitheater. Speakers are expected to include former Rep. Biskupski; Jesse Nix, Utah Pride Center board member; married couple Russ and Joe Baker-Gorringe; and Pastor Erin Gillmore, Holladay United Church of Christ.
"We're going to come together and celebrate the LGBT [lesbian, gay, bisexual, transgender] community and progress," said Valerie A. Larabee, executive director of Utah Pride Center.
In Provo, Brigham Young University students and Utah County residents will rally for marriage equality on Monday from 6 p.m. to 8 p.m. at the Utah County Historical Courthouse. The event will feature speakers, singing and a candlelight vigil.
"We want to add our voices to the many around the nation that recognize marriage as a beautiful thing," said organizer Curtis Penfold.
Vigils around the country are being held as part of an effort by the United for Marriage: Light the Way to Justice coalition.
California's Prop 8 passed with 52 percent of the state's vote, but it was overturned in 2010 by a federal judge, and the 9th U.S. Circuit Court of Appeals affirmed that decision.
The Salt Lake City-based Church of Jesus Christ of Latter-day Saints spent $189,004 on the "Yes on 8" campaign, while businesses and individuals from Utah contributed $3.8 million to the campaign, more than 70 percent of it in support of Prop 8.