Pre-Snowden, I wonder if the ruling would have been different. Back then the judges would only know what was presented to them. The government would have obviously presented in a way that was most favorable to them, and their opposition would not have access to crucial evidence. Now that the cat shit is out of the bag, judges and everyone else have more background to evaluate what's in front of them. The government w…
Previous attempts to litigate the legality of mass collection of data had failed based on problems with the "standing" of plaintiffs. Specifically, the people who sued could only say that it was implicit that the government had collected data on them, but they had no actual evidence that it had happened -- specifically, to them.
That specificity is necessary to have standing in cases against the government, as a longstanding principle that you can't just use the courts to claim the government is violating the constitution or doing something wrong in a general way, you have to present courts with a specific controversy and specific facts that yielded specific damages and have specific redress.
That specificity was provided by Snowden when he turned over copies of the actual subpoena/requests to Verizon by the NSA. The ACLU was then able to say, we are actual customers of Verizon on the dates in question, and this order is asking for actual information on us, specifically.
Without Snowden this issue would never have reached this point and this decision -- which indeed has ruled illegal the NSA's mass metadata collection of telephony records -- would have never happened.