https://www.cato.org/blog/patriot-powers-roving-wiretaps
> For an ordinary non-roving wiretap, that means you show a judge the “nexus” between evidence of a crime and a particular “place” (a phone line, an e‑mail address, or a physical location you want to bug). You will often have a named target, but you don’t need one: If you have good evidence gang members are meeting in some location or routinely using a specific payphone to plan their crimes, you can get a warrant to bug it without necessarily knowing the names of the individuals who are going to show up. On the other hand, though, you do always need that criminal nexus: No bugging Tony Soprano’s AA meeting unless you have some reason to think he’s discussing his mob activity there. Since places and communications facilities may be used for both criminal and innocent persons, the officer monitoring the facility is only supposed to record what’s pertinent to the investigation.