FILE - In this Oct. 4, 2017 file photo, a little-known device called a "bump stock" is attached to a semi-automatic rifle at the Gun Vault store and shooting range in South Jordan, Utah. The Trump administration is moving to officially ban bump stocks, which allow semi-automatic weapons to fire rapidly like automatic firearms. A senior Justice Department official said Tuesday bump stocks will be banned under the federal law that prohibits machine guns. It will take effect in late March. (AP Photo/Rick Bowmer)

DENVER | Republican lawmakers and a Colorado gun rights group are filing a lawsuit to block a “red flag” law allowing courts to order firearms taken away from people who pose a danger, arguing that House Democrats violated a section of the state constitution governing the legislative process.

Opponents of the measure announced their plans Thursday.

Democratic Gov. Jared Polis signed the measure in April. The law places the burden of proof on a gun owner to get firearms back by showing that he or she no longer poses a risk.

The lawsuit’s backers said it focuses on Democrats’ refusal to read the bill’s entire text during floor debate. A spokesman for House Democrats did not immediately respond to a message.

The measure is Colorado’s most significant gun legislation since 2013.

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