Yes, it's very strong legally. Congress or the states can try for a Constitutional Amendment (but those are few and far between, last one was in 1992), or the Supreme Court can later reverse itself partially or in full. An example of that would be Plessy v Ferguson in 1896, where the Supreme Court ruled segregation laws were constitutional, but later in the 50's (Brown v. Board of Education) they reversed it.
Those are the only options if they're ruling on the constitutionality of a certain law. If they're just deciding on whether or not an action violated any given law (as in this case), you could reverse the ruling by changing the law itself (i.e. through Congress).
