Comment by cyphar

Sure, warrants and subpoenas need to exist in order for the legal system to function. However, they have limits.

The modern abuse of the third-party doctrine is a different topic. Modern usage of the third-party doctrine claims (for instance) that emails sent and received via Gmail are actually Google's property and thus they can serve Google a warrant in order to access anyone's emails. The old-timey equivalent would be that the police could subpoena the post office to get the contents of my (past) letters -- this is something that would've been considered inconceivably illegal a few decades ago, but because of technical details of the design of the internet, we have ended up in this situation. Of course, the fact there are these choke points you can subpoena is very useful to the mass surveillance crowd (which is why these topics get linked -- people forget that many of these mass surveillance programs do have rubber-stamped court orders to claim that there is some legal basis for wiretapping hundreds of millions of people without probable cause).

In addition (in the US) the 5th amendment allows you the right to not be witness against yourself, and this has been found to apply to certain kinds of requests for documents. However, because of the third-party doctrine you cannot exercise those rights because you are not being asked to produce those documents.