IANAL, so can someone help me understand: How is this the final say if it's out of a court in Boston? Isn't that only one circuit?
It's definitely a good ruling to have on the books but it could very well just end up being a checkbox matter to have a pretense of "suspicion" (ie "this person appeared nervous").
Depending on the jurisdiction of this district court the DHS might even decide that it doesn't apply outside that jurisdiction until a higher court rules on it.
But yeah, all hangs on what is "suspicion" (or what passes for it in practice), compared to say a targeted op or warrant provided by a court (even if its one of those secret courts like FISA).
Obviously it's not the final word unless it comes from the Supreme Court.
That's why supreme court rulings are such a big deal. They are the ultimate 'root' authority.