Not at the present time there isn't.
> Congress [could] pass a law
Saying that Roberts's appointments are reviewable because Congress could change the law is exactly analogous to saying that murder is legal because Congress could change the law. It is true that Congress could change the law. But unless and until it actually does change the law, murder is in fact illegal, and Roberts's appointments are in fact not reviewable.
I chose a bad example because murder is generally illegal under state law, not federal law (though there are exceptions). But there are things that are illegal under federal law that Congress has the power to change. Those things are in fact illegal (now) notwithstanding that Congress could change the law and make them legal. Likewise, Robert's appointments are not reviewable (now) notwithstanding that Congress could change the law and make his appointments reviewable.
I think this is an interesting but (apparently) subtle argument, so lets take it a step further for illustration purposes.
The US could repeal the first amendment, and explicitly make being a buddhist illegal, if enough congressmen got on board. There is a clear well known process for this, and in fact even precedent as previous amendments have been repealed. This does not make it incorrect to say 'freedom of religion is a inalienable right in the USA', because it is such today, as the law stands, the fact that congress has the power to change this doesn't make it a false statement...
We say that someone is unaccountable when the process required to lead to their accountability subsequent to misbehavior is in practice not likely to occur, not when the absolute lack of accountability can be proven with mathematical rigor.
This is the same pedantry that leads engineers to come up with crazy legal arguments. The fact that velocity is relativistic and relative to an external observer not subject to the rotation of the Earth your vehicle was not exceeding the speed limit is not going to get you out of a speeding ticket, no matter how many times you argue that it's technically correct. Because when people say things they do so within an accepted context that doesn't include the sort of pedantic absolutism that would cause arbitrary good faith statements made in the course of normal conversation to become technically inaccurate when weighed against impossible standards.
This actually ties into the anti-federalist argument against the Constitution and Bill of Rights. Where in the Constitution is Congress authorized to make laws regarding the practice of religion?
The Commerce Clause, of course! I imagine they would argue that money donated to churches would otherwise be used to purchase goods and services. Or that time spent worshipping would otherwise be used in production.
I'm only half joking.
And conveniently enough, who gets to make that call?
How you can argue that this isn't a rigged system is, well, interesting.
(Consider the turnout for the briefings on this nonsense a couple of weeks ago--most skipped out to catch flights home.)
Attending those briefings is a poison pill. Before being briefed, members must swear not to reveal any of the content of the briefing.
Nevermind that politicians being blackmailed is hardly unheard of...
I'm not sure this would be constitutional. Courts have rules that the term limits on FISA judges don't impact their standing as regular article III judges. Arbitrary removal almost certainly would.