I'm a little confused on how leave to file works both in this case and in general. Are you saying that one of the parties involved can move to have the case tried in a lower court? How exactly would that work? Especially since 16 other states have joined Texas....Incidentally though, what's the official process for SCOTUS deciding to hear a case? Is there some kind of codified protocol?
The court can agree with the defendants (PA, et al), refuse to hear it and hold that the plaintiffs (Texas, et al), should have brought it in a lower court first. The codified protocol is (I think) that four of nine justices have to vote to hear it. The general standard for whether they will exercise the original jurisdiction is generally dependent on two factors: (1) “the nature of the interest of the complaining State”; and (2) “the availability of an alternative forum in which the issues tendered can be resolved.”
Plaintiffs are arguing there is no alternative forum given, among other factors, the multi-jurisdictional nature of the case. They are also arguing they (and their citizens) have a compelling interest in seeing that the defendants don't install a president who was elected in violation of the law and, in particular the US Constitution. Defendants, of course, are claiming the opposite.
