WATCH: As Colo. Clerk Issues Marriage Licenses, Same-Sex Couples File Suit

As a county clerk in Boulder, Colo., prepares to defend her decision to issue marriage licenses to same-sex couples against the state attorney general's declaration that those licenses are invalid, a group of six same-sex couples have filed a federal lawsuit aiming to strike down Colorado's constitutional prohibition on marriage equality.

The case, filed Tuesday, is the third taking aim at Colorado's 2006 voter-approved constitutional amendment defining marriage as the union one man and one woman, although it is the first federal suit to challenge the state's law. Two other cases, filed earlier this year in Denver and Adams counties, have been heard in state court and are awaiting decisions.

The six couples who filed Tuesday's suit are diverse in age, gender, raceme and ethnicity, and include an Army veteran, an enrolled member of the Klamath tribe, parents, attorneys, homeowners, and teachers.

One of those teachers and plaintiffs is Kate Burns, a faculty member at the University of Denver, who wants to marry her partner of 11 years, Sheila Schroeder. The couple entered into a civil union last year when Colorado legalized that option for same-sex couples.

"It's very simple: I love Sheila with all of my soul and I pledge to take care of her and grow old together," Burns tells The Advocate. "As a family, we are productive, taxpaying members of our community, and we deserve the same rights and dignity that marriage automatically grants to heterosexual couples."

Burns notes that last week's decision from the 10th Circuit Court of Appeals -- which decides federal cases coming out of Colorado, Utah, New Mexico, Kansas, Wyoming, and Oklahoma -- finding Utah's marriage ban unconstitutional makes this an opportune moment to seek the freedom to marry in Colorado.

"The time is now, especially since the 10th Circuit Court decision in Kitchen v. Herbert, which is a victory for fairness and equality," says Burns. "That decision validates that the 14th Amendment applies to all of us in equal force. Achieving marriage equality in Colorado wouldn't just be a victory for our families, but also for all citizens of Colorado who have a stake in the integrity of our state's laws."

The ruling in Kitchen, which is expected to be appealed to the Supreme Court, is also the justification for Boulder County Clerk Hillary Hall's decision to start issuing marriage licenses to same-sex couples in her county, just west of Denver. Hall contends that the 10th Circuit's decision -- which included a stay while the case is appealed -- effectively invalidates Colorado's constitutional ban on same-sex marriage. As an elected official sworn to uphold the state and U.S. Constitution, Hall says it is her duty to issue marriage licenses to same-sex couples who want them. According to the Los Angeles Times, 88 same-sex couples have received marriage licenses in Colorado since Hall's office began issuing them June 25.

But the state's Republican attorney general says those licenses are invalid, arguing that because the 10th Circuit stayed its decision in Utah, it has no effect on the laws in other states encompassed in the Circuit. Essentially, he argues, the case is still in progress, and therefore its rulings are not yet enforceable.

"The constitutional ban in Colorado on same-sex marriage remains in effect, pending a decision by the United States Supreme Court," Suthers told Denver's KCNC TV Tuesday. The attorney general's office says it is considering legal action against Hall and the Boulder County Clerk's office -- especially since Hall has refused to stop issuing licenses without a court order to do so.

"Just because [the attorney general] says something's not valid, that's not how the law works," Hall told KCNC.

Watch KCNC's report on the new federal lawsuit below.