The District Attorney’s office is attempting to use Harris’ tweets to contradict his defense that demonstrators on the bridge did not hear police orders to vacate the area and had permission to march. Harris and his lawyers from the National Lawyers Guild argue the subpoena is an “unwarranted invasion of privacy.” The San Francisco Gate reports Assistant District Attorney Lee Langston disagrees, writing “he has no proprietary or privacy interest in tweets that he broadcast to every person with access to the Internet.”
The EFF acknowledges this partly, insofar as the government can simply scroll back through a public Twitter feed and get the information they desire. The subpoena however, covers much more than just the public tweets of Mr. Harris:
With this overbroad subpoena, the government would be able to learn about who Mr. Harris was communicating with for an extensive period of time not only through Tweets, but through direct messages. And with the government’s request for all email addresses associated with @destructuremal, they could subpoena Mr. Harris’ email provider to get even more information about who he communicated with.
Beyond that, the EFF points out the government could also be fishing for some other information, mainly location data. The majority of Twitter users are connected via mobile devices, and Twitter keeps track of IP addresses, dates and times related to log ins and messages. Should the government be able to subpoena this information, the ISP would hand over the information the specific cell tower someone uses to access Twitter. Armed with this information, the government would be able to track Mr. Harris’ movements over the past three months, sidestepping the Fourth Amendment.