Law enforcement agencies have come up with a new tactic for investigating crimes: location-based warrants, served on Google, demanding that Google disclose Google accounts in use on all mobile devices that were in a given area at a certain time, thus giving detectives and other LEOs a pool of potential suspects and persons of interest who may have committed or have information about whatever crime they are trying to solve.

California Governor Jerry Brown vetoed a bill on Sunday that would have required a search warrant in order to obtain location-based personal information obtained through cell towers from mobile devices such as cell phones and tablets, and also GPS systems. The veto came with the message that Brown felt that information based on a user’s location is important to the processes needed by law enforcement.

Even though Twitter added location-based information services (“Twitter with Location”) to Twitter a few months ago, Twitter is only just now advising Twitter users that they can opt in to the new Twitter Location feature (it’s turned off by default, so you don’t have to opt out of Twitter with Location). Here’s how to use – and why you should, or shouldn’t use – Twitter’s Location based Tweet information.