@PATAX "IE they were not CPA organizations or EA organizations or tax professional organizations"

They probably wouldn't have had standing and the case would have been tossed out. Such as happened with a lot of the ACA cases.

The gov't did try to argue that NSBA did not have standing, but I guess (I haven't read the 53 page case yet)  the judge didn't agree. Tax Notes mentioned this in a write up about the case that they did about  year ago. It's behind a paywall so I'm not linking it.