Montana has seen many of its laws struck down in the wake the Citizens United decision that opened the door for more corporate spending in federal races, citing freedom of speech issues.
Last month, a federal appeals court struck down Montana's ban on partisan endorsements of judicial candidates, citing Citizens United.
U.S. District Judge Charles Lovell earlier this year ruled as unconstitutional laws requiring attack ads to disclose voting records and a ban on knowingly false statements in such ads.
The Supreme Court also tossed the state's century-old, voter-approved ban on independent corporate political spending in state races.
That decision prompted a new ballot initiative that, if approved in November by voters, asks state leaders to seek a constitutional amendment undermining the high court's decision.