Will what's good for the Goose, in this case Guam, be good for everyone else?

No provision of the murky Federal Superfund statute is more murky than Section 113, the applicable statutes of limitations.  For decades Judges have struggled with what is the "completion of response actions", what is a "removal action" and what is a "remedial action", and other minutia that determine whether or not a multi-million dollar contribution claim is viable. 

Now the Supreme Court is going to take a swim in the murky waters of Section 113.  At issue is whether the Territory of Guam can recover from the United States Navy some part of the hundreds of millions of dollars it is spending as a result of contamination from a former Navy Base in the Territory.  There's absolutely no doubt that the United States Navy caused the contamination that the United States EPA then ordered Guam to clean up.  When Guam later came back at the Navy, the Navy said that too much time had passed since Guam's settlement with EPA for Guam to seek any of the costs of that settlement on the Navy. 

I think the Supreme Court will find in Guam's favor, including because the three year statute of limitations the Navy says controls applies to only to Superfund settlements and the settlement at issue was under the Clean Water Act, but also because the Court will be disinclined to reward what my Grandfather would have called chutzpah.

Despite all of that, contribution claims are not like fine wine.  They generally don't age well at all so sorting out one's affairs with potential contribution defendants sooner rather than later is usually the best course.