A 2012 ruling upholding Nevada's ban on gay marriage has been appealed by plaintiffs in the case.

According to the AP, Lambda Legal, which is representing 8 Nevada couples in the case, appealed the ruling on Friday, asking the 9th U.S. Circuit Court of Appeals in San Francisco to review the case.

U.S. District Chief Judge Robert Jones ruled that the U.S. Constitution's guarantee of equal protection does not prohibit “the People of the State of Nevada from maintaining statutes that reserve the institution of civil marriage to one-man – one-woman relationships.”

In reaching his conclusion, Jones rejected arguments that gay men and lesbians have historically faced discrimination.

“Homosexuals have not historically been denied the right to vote, the right to serve on juries, or the right to own property,” Jones wrote.

The lead plaintiffs in the case are two women in their 70s who have raised 3 children and have 4 grandchildren. Beverly Sevcik and Mary Baranovich have been together more than four decades.

In 2002, Nevada voters overwhelmingly approved a constitutional amendment defining marriage as a heterosexual union. Nevada in 2009 began recognizing gay and lesbian couples with domestic partnerships, which offer far fewer benefits than marriage.

In April, lawmakers gave initial approval to repealing the ban and legalizing gay nuptials in Nevada. A second vote is needed before going to voters in 2016.

(Related: Nevada Senate approves resolution on gay marriage.)