Sometime this fall, the U.S. Supreme Court will take up a case that court decide the future of the Endangered Species Act – or, at least, the future of the “critical habitat” provisions that have played such a huge role in shaping California’s land-use patterns over the last generation.

Weyerhaeuser v. U.S. Fish & Wildlife Service could be the first big test of Brett Kavanaugh – if he is seated as Justice Anthony Kennedy’s successor – in the environmental and land use arena. At first glance, it would appear that Kavanaugh would likely favor the landowner in this case, especially given his D.C. Circuit ruling in a similar case from Otay Mesa in San Diego back in 2011.

But the question isn’t that clear-cut. Is Kavanaugh a pro-business judge who’s anti-environment? Or does he see himself instead as a strict guardian against regulatory overreach. It may not make much difference in the end. But if Kavanaugh really is focused on holding the regulatory agencies’ feet to the fire, maybe he’s not an automatic anti-environment vote in all cases.

With the possible exception of the definition of wetlands – which the Trump Administration is trying to change – no environmental is more influential in shaping California’s land-use patterns that critical habitat designation under the Endangered Species Act. For all intents and purposes, developers can build on critical habitat – because they can’t disturb the habitat itself. Oftentimes, developers and government agencies choose instead to create a habitat conservation plan, which lays out areas that can be developed and areas that cannot. Virtually every developing area on the suburban fringe in the whole state – from Yolo County down to Riverside and San Diego – has been profoundly affected by either the fact or the threat of critical habitat designations.

And Weyerhaeuser could profoundly alter how that process works, depending on how it’s decided.

Weyerhaeuser involves several thousand acres in Louisiana that was designated by the Fish & Wildlife Service as critical habitat for the dusty gopher frog. The frog itself wasn’t found on the Louisiana property – but, rather, only on nearby property in Mississippi. But the Fish & Wildlife Service determined that survival of the species required not only the property where the frog was found, but habitat where the frog could thrive but was not found, because isolated ponds such as those found on the Louisiana property were

This finding was the basis for the Fifth Circuit’s ruling in favor of the Fish & Wildlife Service in the Weyerhaeuser case. The Fifth Circuit concluded that “all of the experts agreed that designating occupied land alone would not be sufficient to conserve the dusky gopher frog” and isolated ponds in geographically discrete locations were necessary for the species’ survival.

In Otay Mesa, Kavanaugh’s ruling overturned a decision by the Fish & Wildlife Service to declare 143 acres of land in the Otay Mesa section of San Diego as critical habitat for the fairy shrimpx But in that case, the Fish & Wildlife Service didn’t base its critical habitat ruling on the notion that unoccupied territory was necessary for survival of the species. Rather, the Service argued that the fairy shrimp was present – even though it had been found only once in eight attempts to find it, and then four years after it was listed.

So, in that case, Kavanaugh’s ruling represents the kind of regulatory “gotcha” that he’s known for. Maybe if the Service had determined that the Otay Mesa property was vital to the species even if the land was unoccupied, he would have ruled the other way. But they didn’t, and he didn’t.

Or maybe not, and that’s the big question about Kavanaugh.

Like many regulatory rulings involving endangered species, wetlands, and other environmental issues that can affect land-use patterns in California, the Fifth’s Circuit’s ruling in Weyerhaeuser depends largely on the court’s interpretation of Chevron, U.S.A., Inc. v. Nat. Res. Def. Council, Inc., 467 U.S. 837, 843 (1984). In this environmental challenge to the Reagan-era Environmental Protection Agency’s interpretation of the Clean Air Act, the U.S. Supreme Court ruled that, if congressional direction is not clear in a statute, then the court must give deference to the regulatory agency interpreting the statute. (The EPA administrator at the time was Anne Gorsuch, mother of the Trump-appointed Supreme Court Justice Neil Gorsuch.)

This ruling gives judges a lot of wiggle room in overseeing regulatory agencies. If they decide a law does not provide a regulatory agency with direct guidance, they can invoke the Chevron rule. If they decide the law is clear, they can say the Chevron rule doesn’t apply.

In Weyerhaeuser, the Fifth Circuit decided that the Chevron rule applies. In the Endangered Species Act, the court ruled, Congress did not provide a specific definition of habitat that is “essential” to the conservation of the species but, rather, left that decision up to the Secretary of the Interior. And so the Fish & Wildlife Service had the discretion to decide whether unoccupied territory was essential to the preservation of the frog.

But here’s the thing: Other than the highly publicized issues about presidential power, nothing in Kavanaugh’s record has drawn more attention so far than his criticism of the Chevron rule.

In a 2016 book review in the Harvard Law Review, Kavanaugh called Chevron “an atextual invention of the courts” that is “nothing more than a judicially orchestrated shift of power from Congress to the Executive Branch.” He said that whichever party is in power will use seek to use Chevron aggressively to pursue its agenda. In the law review – as on several other occasions – he has said it is difficult to know when to apply the Chevron rule and when not to.

So the question for California land use is how will Kavanaugh approach the Chevron question in the Weyerhaeuser case. If he decides that Chevron shouldn’t apply – and he’s the deciding vote on the court – then the Fish & Wildlife Service will be boxed in on critical habitat much more than it is now and landowners will have much less motivation to engage in HCPs.

But is that what Kavanaugh would really do? Opinions are all over the place. Some say he wants to overturn Chevron – and maybe Weyerhaeuser is the case he would want to use to do it. Others say he just wants to box it in. Still others, however, say that because he finds Chevron difficult to apply, he’ll actually avoid applying it whenever he can – and that is the most likely scenario in the Weyerhaeuser case.

The Trump Administration is likely to seek major changes in endangered species and wetlands laws. But even without legislation, will interpret those laws very differently than the Obama Administration. (The Administration’s attempts to repeal Obama’s “WOTUS” rule is a good example.) The Supreme Court will inevitably call, as Chief Justice John Roberts puts it, “balls and strikes” on these interpretations. If Kavanaugh is confirmed, the size of his strike zone on Chevron is likely to have a significant impact on California’s future land use patterns, especially in the Inland Empire and the Central Valley.