The ITC can definitely adjudicate invalidity.
I actually don't know for certain and I was in Google Patent Litigation (as tech advisor). I never had a case before the ITC so I can't say 100%, but AFAIK only the PTO or a regular Federal court can declare a patent invalid.
But maybe they can say "well, this will probably be declared invalid, so we're going to stay the order." Like a German court can do. So please tell us one way or the other.
"Infringement, validity, and/or enforceability" constrained to section 337, per the above legal analysis.
IANAL
OK, we're splitting hairs, but an ITC determination that your patent is invalid doesn't render it useless in other contexts.