Decisive: if the decision was not made, there's a good chance that the other party would've won. SCOTUS must reasonably believe it to be likely decisive (as with Bush v Gore). So that's likely to happen directly after the election, or something that e.g. makes Pennsylvania impossible to win for one party
Controversial: decided by me, in conversation with traders, based on a high level of controversy in the mainstream legal community.
Bush v Gore would be classified as 'Yes, in favor of Republicans', even though some recounts still had Bush winning.
https://en.m.wikipedia.org/wiki/Bush_v._Gore
I will not bet in this market.
Companion question:
https://www.vox.com/scotus/367701/supreme-court-arizona-rnc-republicans-mi-familia-vota
Adding some clarification based on this voter suppression case in Arizona case: SCOTUS must reasonably believe it to be likely decisive (as with Bush v Gore). So that's likely to happen directly after the election, or something that e.g. makes Pennsylvania impossible to win for one party