One of questions raised by the election of President Donald Trump is how his appointments to the Supreme Court (with the “advice and consent” of the Senate) may influence the future direction of the nation’s environmental law. The pending nomination of Judge Neil Gorsuch to fill the Court vacancy created by the death of Antonin Scalia makes the question especially timely.

The Supreme Court plays a crucial role in shaping the nation’s environmental law. Except in exceptional cases governed by federal common law, involving interstate water disputes, for example, the Court itself does not create environmental law. Instead, it typically reviews environmental measures generated by the other branches of government to see whether they are consistent with statutes enacted by Congress or the U.S. Constitution.

But this Court power to check the other branches greatly influences the ultimate content of the law, as illustrated by two relatively recent decisions, one upholding Environmental Protection Agency (EPA) authority to regulate greenhouses gas as “air pollutants” under the Clean Air Act, and another declining to uphold EPA regulations defining the scope of federal permitting jurisdiction over wetlands under the Clean Water Act.

How justices decide cases traditionally reflects the ideology of the presidents who appointed them. Justices appointed by Democratic presidents typically support government action to protect the environment, while Republican-appointed justices tend to be skeptical of environmental regulation. There are notable exceptions to this pattern; after all, Supreme Court justices have life-time tenure, making them beholden to no one. Nonetheless, party association is, for better or for worse, a reliable predictor of how justices vote.

President Trump might be viewed as a wild card in the judicial selection process because his views sometimes diverge from Republican Party orthodoxy. He has joined many other Republicans in criticizing President Obama’s Clean Power Plan to combat climate change, but he departs from most Republicans in in supporting aggressive use of the eminent domain power to promote private economic development. Will Trump’s judicial appointments be idiosyncratic as well?

The evidence suggests not. During the campaign, Trump released a list of potential candidates to fill the vacancy on the Court and, true to his word, once elected; he nominated a person from that list, Judge Gorsuch. Trump has publicly acknowledged the help he received in compiling his list from the Heritage Foundation and the Federalist Society, two deeply conservative organizations with a laser-like focus on how judicial appointments can advance the conservative agenda.

So what is the potential effect of Judge Neil Gorsuch likely joining the high court on environmental law? The answer depends a great deal on one’s perspective. Some critics of the appointment lament that the Senate did not take up President Barack Obama’s nomination of federal appeals court Merrick Garland. They point out that President Trump has an opportunity to fill a vacancy on the Court only because the Senate failed to act to fill the vacancy earlier. Confirmation of Garland would have created the first Democratic-appointed majority on the Court in decades, and the likely confirmation of Gorsuch instead represents a significant change. On the other hand, supporters of Gorsuch point out that he will fill a seat held by the late Justice Scalia, a staunch conservative, suggesting that Gorsuch represents ideological stability on the Court.

Gorsuch has participated in a only a handful of environmental law cases during his ten years on the U.S. Court of Appeals for the Tenth Circuit, making it difficult to draw any firm conclusions about his stance on environmental law issues. The judge is a skier and an angler, suggesting he might be sympathetic to environmental concerns; but Justice Scalia’s enthusiasm for trout fishing certainly did not temper his skepticism about environmental regulation! It is interesting to observe that Judge Gorsuch’s mother, the late Anne Burford Gorsuch, was a very controversial EPA Administrator under President Ronald Reagan.

Gorsuch has staked out positions on several crosscutting legal questions that have important implications for environmental law, leading advocacy groups as the Sierra Club and the Earthjustice Legal Defense Fund to come out against his confirmation. Critics of government regulation sometimes seek to apply the so-called nondelegation doctrine, which purportedly limits the power of Congress to make delegations of rule-making authority to administrative agencies. The Supreme Court has upheld nondelegation challenges to congressional enactments in only a handful of cases, both decided in the 1930’s, and the late Justice Scalia wrote an opinion for the modern Court rejecting a nondelegation challenge to the Clean Air Act. In a highly visible dissent filed in 2015, however, Judge Gorsuch offered a full –throated defense of the doctrine, suggesting he might try to lead an effort on the Supreme Court to breathe new life into the doctrine, an ominous prospect for modern environmental statutes that are commonly drafted with a broad brush.

Gorsuch also has written opinions suggesting sympathy for the argument that courts should be reluctant to recognize that private environmental plaintiffs have “standing.” Article III of the Constitution limits the judicial power to “cases and controversies,” giving rise to the Court-made doctrine that plaintiffs must meet various requirements to establish their “standing” to sue in federal court. In a 2013 case, Gorsuch filed an opinion taking a strong stance against the Wilderness Society’s attempt to challenge a western county’s creation of public roads on protected federal lands. In another case he argued against allowing environmental advocates to intervene in a case to defend a plan to limit off-road vehicle use in the national forests. Given President Trump’s policy to reduce regulations, potential new judge-made constraints on citizens’ ability to sue to enforce environmental laws are a matter of concern for environmental advocates.

Gorsuch is perhaps best known for staking out, just in the last year, a very strong and public position against the so-called Chevron doctrine, which grants federal administrative agencies broad latitude to interpret ambiguous federal statutes. Critics of the Chevron doctrine, including Gorsuch, say it gives too much power to unelected bureaucrats and undermines the function of the courts to define the law. Defenders of Chevron say that expert agencies need some latitude in implementing complex and often ambiguous statutory provisions and that agency officials are under the ultimate control of elected officials. Critics express concern that Gorsuch might pursue his anti-Chevron agenda to the point of hamstringing federal agencies, particularly in the environmental arena. Ironically, however, Chevron applies both to agency rules adopting regulations and those loosening regulations; in other words, in the era of Trump, discarding Chevron might constrain the President’s stated goal of reducing regulatory burdens,

Beyond the nomination of Judge Gorsuch to the high court, President Trump might have the opportunity to make additional appointments to the Court. Several of the more liberal justices on the Court have served for many years, creating the possibility that President Trump will have the opportunity to replace relatively reliable votes in favor of environmental protections with justices that would vote differently. With the opportunity, over the next four or eight years, to fill as many as three or four vacancies in the Court, President Trump has the potential to change, and almost inevitably weaken, environmental law in ways that are hard to predict.