The Supreme Court is meeting in private on Friday to decide which same-sex marriage cases to accept for review, and it is expected to announce its decisions by Monday.

The court is not deciding on the merits of the cases, just whether to take them. Pending are a handful fo challenges to the Defense of Marriage Act, and also the challenge to California’s Proposition 8. It’s the latter case that has the most involvement of industry activists, who financed an effort to overturn the state’s ban on same sex marriage, winning victories in district and appellate courts.

What will have the most immediate impact is if the Supreme Court decides not to take the Prop 8 case. That would mean that the lower court rulings declaring the initiative unconstitutional stand, and presumably that same-sex marriages in the Golden State can proceed.

The American Foundation for Equal Rights is planning a press conference call 30 minutes after any action, with lead counsel Ted Olson and David Boies and HRC president Chad Griffin. They also are planning a press conference if there is a decision on Monday. LGBT POV‘s Karen Ocamb reports that if cert is denied to the Prop 8 case, and the marriages set to resume, plans are for a rally at Grant Park Performance Lawn in downtown Los Angeles, with Rob Reiner as the MC. West Hollywood and Long Beach also are planning celebrations that evening. Los Angeles and San Francisco are making preparations, and have asked the Ninth Circuit for advanced notice if the court is about to issue a mandate lifting a ban on gay nuptials.

The wisdom seems to be that there is a strong likelihood of the court taking one or some of the DOMA cases but not the Prop 8 case.

Richard Socarides, New York lawyer and Democratic strategist, said that while it is “very hard to predict” what the high court will do, there is a sense that the Supreme Court “doesn’t like to decide what it doesn’t have to decide.”

While there’s reasoning that the court could still see the issue better left to the states, the Ninth Circuit decided Prop 8 on narrower grounds than the district court. The appellate judges’ rationale was that Prop 8 was unconstitutional because it denied rights previously granted, citing a decision that the court made in 1996 when it struck down a Colorado anti-LGBT rights law. That is far different than declaring that the constitution guarantees a right to same-sex marriage, and the narrower ruling could make it easier for justices to take a pass.

But with just four votes needed for the court to accept a case, the court is, as Socarides says, “very hard to predict.” Remember last summer’s healthcare ruling and who ultimately turned out to be the swing vote.