It is of course too soon to know (but never too soon to speculate)!
While still a candidate, President-elect Trump released two lists of potential Supreme Court nominees to fill the current vacancy on the Court. While he has indicated that these lists are definitive, only time will tell whether he will in fact stick to them when making a nomination. Both lists were well-received by conservatives.
President Trump should have little trouble getting a conservative nominee through the majority-Republican Senate. If Senate Democrats filibuster Trump’s nominee, Senate Republicans are likely to exercise the “nuclear option,” meaning only a simple majority of Senators will be needed to confirm the nominee.
Assuming all goes according to plan, a conservative Justice will replace another conservative Justice, Justice Scalia, some time next spring. But of course no two Justices are interchangeable especially a Justice like Justice Scalia who was guided by originalism and textualism and didn’t always tow the party line on issues like, for example, the Fourth Amendment.
What does this mean for state and local governments?
Conservative Justices tend to be good for state and local governments on issues like public employment, qualified immunity, and the Fourth Amendment. In theory, conservative Justices are better for state and local governments on preemption and federalism, but often these consideration are clouded by the facts of the case.
Liberal justices tend be more deferential to the government generally and better for state and local governments on land use and tax issues. And, of course, liberal Justices are more likely to advance social issues, which state and local governments are often divided on.
These days no Justices are great for state and local governments in First Amendment cases!
In short, it is difficult to imagine that President Trump’s first Supreme Court nominee will shift the Supreme Court much at all. So, in terms of the Supreme Court, state and local governments are likely to be in much of the same position they have been in recent history.
Additional appointments are likely in the next four years though not inevitable. The average retirement age for Supreme Court Justices is 79. The oldest Justices currently on the Court are liberals and “swing” Justice Kennedy: Justice Ginsburg (age 83), Justice Breyer (age 78), and Justice Kennedy (age 80).
If President Trump makes multiple appointments to the Supreme Court the Court will likely have a larger majority of conservative Justices (who will no longer need Justice Kennedy’s vote in cases involving social issues).
The biggest change for now on the Supreme Court likely to impact state and local governments (and others) could be the cases the Court will consider. Ilya Shapiro blogging for CATO at Liberty explains: “If you live by executive action, you die by executive action—which means that many high-profile cases looming on the Supreme Court docket will simply go away. DAPA (executive action on immigration) and the Clean Power Plan will be rescinded, religious nonprofits will be exempt from Obamacare, Trump’s HHS won’t make the illegal payments that have led to House v. Burwell, and more. That may include the transgender-bathroom guidance, which if rescinded would remove the biggest controversy from the Court’s current term.”
Again, only time will tell.