HELENA — The U.S. Supreme Court said Feb. 19 that it won’t take up a legal challenge to Montana’s 2015 Disclose Act, leaving the state’s flagship anti-dark-money legislation intact.

The 9th U.S. Circuit Court of Appeals last year ruled against the challenge, which was brought by a group called Montanans for Community Development.

The MCD group said the Disclose Act had dissuaded it from sending out issue mailers in the 2016 election because it didn’t want to comply with the act’s political committee reporting and disclosure requirements. The state’s laws, the group argued, were vague, overbroad, and violated constitutional protections of free speech.

The Disclose Act requires additional financial disclosure by political committees that spend money to influence an election and adds additional reporting deadlines. The law also bars coordination between political campaigns and outside groups. In doing so, the Disclose Act sought to minimize the impact of “dark money” spending, in which the identities of donors aren’t available to the public.

The act, sponsored by Sen. Duane Ankney, R-Colstrip and carried by Rep. Frank Garner, R-Kalispell in the House, passed the 2015 Legislature with bipartisan support. It was signed by Gov. Steve Bullock, a Democrat, and has been defended in court by Attorney General Tim Fox, a Republican.

The announcement comes a month after the Supreme Court declined to hear a challenge to Montana’s contribution limits for state and local campaigns, which are among the strictest in the country. That leaves both disclosure requirements and contribution limits the law of the land.

“It’s a very good day for Montanans,” said former Commissioner of Political Practices Jon Motl, who called both laws “among the best in the nation.”

The Disclose Act, Motl said, also requires electronic campaign contribution filing, which makes it easier for the public to examine election-season campaign finance data in a timely manner.

“For over 100 years we have led the way in clean government and transparent elections, despite attempts by out-of-state interests to time and time again overturn the will of the Montana people,” Bullock said in a statement. “This is another victory Montanans can claim over the big money that wants to make our decisions for us.”