Supporters say the law would put reasonable restrictions on the time, manner and place of protests to ensure that “critical infrastructure” such as pipelines, railroads, refineries and telephone lines can continue operating.

“What this bill tries to do is strike a balance between the need to protect our critical infrastructure in the state while also maintaining” First Amendment rights, Sen. Lincoln Hough, R-Springfield, the sponsor of the proposal, told a Senate utilities committee last month.

But opponents, including the Sierra Club, say the idea would have a “chilling effect” on protests by environmental activists or landowners whose property is crossed by the projects in question.

Besides targeting punishment for individuals, groups that organize protests also could face penalties. The legislation subjects organizations to fines if the group “is found to be a conspirator with persons who are found” trespassing or damaging private property.

“Under this law, an organization could conceivably be liable for a fine of up to $100,000 for involvement in planning a protest in which trespassing occurred — even though no trespassing (was) contemplated at the time of the plan,” Michael Diel, of the Missouri Chapter of the Sierra Club, said at the hearing.