The simplest and fastest: A per curiam (unsigned) paragraph saying having considered the briefs and oral argument, the ruling of the DC Circuit is affirmed.
More likely: A set of at least three different opinions, with one robust one saying Presidential immunity has no basis and would go against the entire Constitutional framework, plus a concurring one (including CJ Roberts and possibly Gorsuch and/or Kavanaugh) saying “there may be immunity for some things, which we’re not faced with deciding today, but not for what the defendant is charged with in this case because violating the Constitutional transition of power could never be considered an official act."
Then a dissent (Thomas, Alito, ??? anyone else?) saying “Presidents are totally immune no matter what.”
The Court has a wide range of options.
The simplest and fastest: A per curiam (unsigned) paragraph saying having considered the briefs and oral argument, the ruling of the DC Circuit is affirmed.
More likely: A set of at least three different opinions, with one robust one saying Presidential immunity has no basis and would go against the entire Constitutional framework, plus a concurring one (including CJ Roberts and possibly Gorsuch and/or Kavanaugh) saying “there may be immunity for some things, which we’re not faced with deciding today, but not for what the defendant is charged with in this case because violating the Constitutional transition of power could never be considered an official act."
Then a dissent (Thomas, Alito, ??? anyone else?) saying “Presidents are totally immune no matter what.”