A documentary slamming Colorado liberals, and Democratic Gov. John Hickenlooper, can be aired without disclosing its backers, a federal appeals court in Denver ruled 3-0 in a decision released Tuesday.

Citizens United, the conservative group that won the federal landmark case about campaign finance disclosure in 2010, made the film in question, "Rocky Mountain Heist." Citizens United on Tuesday said the film "explores the liberal takeover" of a once- reliable red state.

The organization argued its documentary should be considered part of the protected free press, such as print or TV news, which does not have to disclose its sources of income.

"Today the 10th Circuit embraced the First Amendment and issued an emergency injunction ensuring that Citizens United can bring its latest film, 'Rocky Mountain Heist,' to the people of Colorado," said David Bossie, the group's president, in a statement.

"Our film and its message are at the core of political speech protected by the First Amendment. For far too long Colorado's campaign finance laws have burdened some speakers while protecting others. Today's ruling is an important first step in overturning this discriminatory law."

Colorado Secretary of State Scott Gessler deemed the film electioneering and required disclosure. U.S. District Court Judge R. Brooke Jackson agreed last month.

Citizens United sought an "emergency injunction" to get the film out before the Nov. 4 election.

The appeals court said that while the movie is exempt from disclosure, the secretary of state's office could require disclosure for ads about it, if the ads name a candidate and make a case for support or defeat. A formal order explaining the decision is expected to follow.

The Colorado secretary of state's office is still deciding whether to appeal.

Martha Tierney, an attorney representing the state Democratic Party, which intervened in the case along with party officials and a voter, cheered the portion of the ruling that upholds the state's voter-approved laws requiring disclosure of donors.

"We are very pleased with the order," she said. "The order makes clear that advertising is subject to disclosure."

Democrats are more worried about a big-dollar advertising campaign attacking Democrats but ostensibly tied to the movie. It's unlikely the movie will draw huge viewership.

A spokesman for Citizens United said "Rocky Mountain Heist" will be shown on cable TV, on a website for the film and possibly via other venues.

The secretary of state's office on Tuesday reiterated that campaign finance rules are derived from vague parts of the Colorado constitution and that the office is required to spend time and money defending cases, including those with a probable chance of losing in the federal courts.

Joey Bunch: 303-954-1174, jbunch@denverpost.com or twitter.com/joeybunch

Staff writer John Frank contributed to this report.