Normally law enforcement conducts its investigations through warrants, which are needed to conduct searches or seizures. Warrants require probable cause–which is specific facts that make it reasonable to believe that a specific person is involved in a specific crime. Warrant-less searches (with exceptions that take up an entire semester of constitutional criminal procedure) are inadmissible.
Subpoenas are different than warrants. Once a trial date is schedule by the court, either the judge or attorneys in their role as officers of the court can issue subpoenas demanding that people produce themselves to testify, produce specific documentation, or come to testify with documents in tow. Subpoenas are not limited to criminal law–as we occasionally serve them in family law matters.
The Comprehensive Drug Abuse Prevention and Control Act of 1970 allows the authorities to make demands for that data in the form of an “administrative subpoena”–a subpoena issued without any pending judicial proceeding. So, as long as there is an investigation, then any Federal Agency can issue the administrative subpoena without even a showing of probable cause. Until recently the 9th Circuit had not yet ruled on the constitutionality of issuing administrative subpoenas that aren’t supported with evidence of a crime.
Below is what the 9th Circuit had to say about it. Basically, the Federal government is saying, “Forget warrants, lets just call it something else and get it without probable cause!”
“The information subpoenaed does not need to be relevant to a crime; in fact, it may be used to dissipate any suspicion of a crime.”
– Judge William Fletcher, in a Ninth Circuit decision ordering utilities companies to turn over customer records even without a warrant. The case, U.S. v. Golden Valley Electric Association, deals with Alaskans suspected of growing marijuana indoors.