The judiciary would be exercising "raw judicial power" were it to overturn Colorado's traditional marriage amendment, an attorney at a religious liberty advocacy firm said Monday.

The court at Adams County District Courthouse in Brighton heard oral arguments in Brinkman et al. v. State of Colorado June 17 – a suit against the state's marriage amendment.

"If this judge were to come to a conclusion other than to uphold the will of the people of the state of Colorado, as expressed in the constitutional amendment passed in 2006, and the laws of the state legislature that define marriage as the union of one man and one woman, it would be an exercise in raw judicial power," Michael Norton, senior counsel with Alliance Defending Freedom, told CNA in an interview outside the courthouse following the hearing.

The lawsuit began last October when a lesbian couple, Rebecca Brinkman and Margaret Burd,  sued the county clerk and recorder for refusing them a marriage license. Civil unions have been legal in Colorado since March of 2013, but the couple wanted a marriage license.

Marriage is recognized in the state as between one man and one woman, according to Amendment 43, which was passed by a majority of voters in 2006.

The brief by the defendants representing the state argued that "redefining marriage would likely harm marriage's inherent connection to procreation, communicating to the community that marriage's primary end is to affirm adult desires rather than serve children's needs, and suppressing the importance of both mothers and fathers to children and their development."

Attorney John McHugh, representing the plaintiffs, said the marriage amendment denied the couples the "dignity" of the recognition of "marriage," as well as their ability to file joint tax returns and receive federal marriage benefits.

"The plaintiffs bring these claims because the marriage bans actively and significantly harm them and their children," he said.

The two parties clashed over the interpretation of last year's Supreme Court decision United States v. Windsor.

Michael Francisco, the assistant solicitor general for the attorney general's office, insisted that the decision "made clear" that it wouldn't invalidate existing state marriage laws.

"Almost the entire substance of the majority opinion in Windsor is premised upon the important historical and traditional power of states to define marriage," he argued.

Norton echoed that reasoning: "the majority of the Supreme Court really left unresolved any issue of how, if at all, state marriage laws should be regulated. It's up to the state to decide, and it's up to the state elected officials to decide, and the people to decide."

However, the plaintiffs asserted that Windsor requires state bans on same-sex marriage to be struck down.

"The sole purpose and effect of these laws is to demean and degrade same-sex couples. The Supreme Court found that that singular purpose invalidated DOMA and Justice Scalia and 14 federal court judges have reason that Windsor's holding requires striking down state same-sex marriage bans," McHugh stated.

McHugh also cited divorce laws to argue that marriage is not primarily about childbearing, because marriages can be ended for "any reason whatsoever." However, Francisco insisted that was exactly the reason why marriage must not be re-defined.

"When states debated, not through the courts but through the legislative process, changing and liberalizing the divorce laws, there was an argument that this was going to change the institution of marriage," he explained, adding that "it's not fair to say that changing the nature of marriage by adopting liberalized divorce laws did nothing to change the institution of marriage."

In the same way, he told district judge C. Scott Crabtree, "if you join with those 18 lower courts, you will be changing what marriage is in Colorado. It will have a real-world consequence. Or, if you're not willing to go that far, all you have to understand is that it is quite reasonable to believe it will have real-world consequences."