You don't have to have a sound legal theory that will hold up in court. You just have to have a sound bite that you can vomit up when someone says "Wait a minute, isn't that blatantly illegal?"
At least in the context of the presidential surveillance program, the ACLU did sue to make them stop. But the program was classified which made getting evidence of the program's existence a crime. The supreme court ruled that they couldn't make a decision without evidence. Shortly after, Snowden leaked the evidence the supreme court had requested. That leak provided the ACLU the evidence necessary to bring the case back to the supreme court and win, "stopping" the program.
Wasn’t this exact route taken? Government got cases dismissed for lack of standing - plaintiff could not prove they were being spied on… because the government wouldn’t reveal anything.
"We're going to sue you to make you stop" is exactly where you deploy the semilegal sound bite. You then use that as the public justification to stall, deny, countersue, delay, appeal, defend, depose and do everything you can to avoid a decision happening one way or the other until you've already gotten and done what you wanted to get and do.
