"Albert Gidari, Director of Privacy for the Center for Internet and Society at Stanford Law School, told us he agrees with the EFF’s argument:
Asking for metadata on everyone that visits a particular website implicates more than just the particularity required by the 4th Amendment. It implicates the 1st Amendment rights of anyone that visited the site.
The [government] is obligated in such cases to ensure that they are using the least intrusive means of obtaining whatever evidence they are searching for. […] On the face of it […] this kind of warrant is overbroad.
He told us that warrants this broad are rare, and they are often later narrowed by the courts:
In the many years I represented online providers in responding to such requests, I’ve seen very few such warrants, and when the warrants were challenged, the courts narrowed or delimited them.
But Jennifer Granick, a former Director of Civil Liberties in the same Stanford center as well as a former director of the EFF’s civil liberty division, told us it’s hard to know for sure how common this phenomenon is:
The truth is we don’t know how often this kind of abuse happens. Sometimes the provider pushes back and comes to a deal with the investigators. A further subset of those times, the provider has to challenge it in court. Not generally for subpoenas, but for other kinds of legal process seeking this type of information, the government routinely gets a gag order which prevents the provider from disclosing the problem, and any court litigation is sealed. This secrecy hides the full truth from the public."