President Trump on Thursday announced that his administration is vastly narrowing the scope of a 50-year-old law governing environmental reviews of large infrastructure and energy projects.

Why it matters: The proposed changes to the National Environmental Policy Act (NEPA) will make the process to review big-ticket fossil-fuel projects like the Keystone XL Pipeline easier and faster, while also excluding consideration of climate change.

It is the first major change to the Nixon-era law in more than three decades, per the New York Times.

The big picture: The move is the latest in dozens of regulatory rollbacks the Trump administration has pursued since 2017, many of them focusing on environmental issues.

Trump campaigned on undoing the Obama administration's aggressive environmental and climate agenda, though in many cases Trump has gone even further than simply rolling back regulations — such as Thursday's move.

Details: The change will streamline the process for acquiring approval for the projects — limiting agencies to a two-year timeline for conducting their comprehensive environmental reviews.

It would limit the range of which projects call for a government review by creating a category for non-major projects, which would not require review. Projects that do not have major federal funding or involvement would no longer require assessment.

Agencies will be able to ignore "cumulative" consequences of major infrastructure projects — which courts have interpreted as weighing a project's impact on climate change.

Instead of seeking approval for projects from the relevant agencies individually, the government would be required to issue one decision on any given project.

What he's saying: Trump said projects are "tied up and bogged down by an outrageously slow and burdensome federal approval process," referring to it as "big government at its absolute worst."

The other side: Environmental groups and Democratic politicians condemned the move. Richard Revesz, a professor of environmental and regulatory law at NYU School of Law, said the rule change could ultimately — and ironically — prolong reviews even more because critics will sue, tying up the projects in court.

What we're watching: To what degree companies building projects that undergo NEPA reviews will seek to do more comprehensive reviews than the law requires to defend against likely lawsuits, per Axios' Amy Harder.

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