Fifty years ago this month, President Richard Nixon signed one of the most effective laws ever written to protect the environment and strengthen democracy by ensuring that citizens would have a say over projects like highways and pipelines that directly affect their well-being.

Now President Trump is trying to cripple it.

New rules that he proposed on Thursday for carrying out the law would strike at the heart of the public’s right to know what our government is doing or failing to do on our behalf and to speak to the lasting impact those actions might have.

Often called the Magna Carta of environmental law, the 1970 National Environmental Policy Act requires that major energy and infrastructure projects receiving federal funding or requiring federal approval must undergo environmental reviews. Citizens have a right to weigh in on these proposals in hearings and through a public comment process.

Mr. Trump’s proposed changes would reduce the number of projects subject to such reviews, by setting new criteria for what qualifies as a major federal action requiring review by excluding projects deemed to be “minimal.” It’s not possible, from the vague language in the proposed rules, to predict which kinds of projects might escape reasonable review, but the enthusiastic response to the proposed changes from the oil, gas and construction industries offers a clue. As more projects are exempted, less information will be available about their potential impacts on communities and the environment.