The 2nd U.S. Circuit Court of Appeals has ruled Section 215 of the Patriot Act illegal under federal law but did not rule on constitutionality. Dane Kennedy reports back on a recent seminar discussion that provides historical perspective on this issue.

When the National Security Agency’s massive program to data mine phone, e-mail, and other electronic records was revealed in 2013, many of us were shocked and appalled by this intrusion into our private lives. How could this program be legal? Authorities insisted that it was, pointing to Section 215 of the Patriot Act. But is Section 215 itself constitutional? “No” is the emphatic answer Laura Donohue gave in her compelling lecture at the German Historical Institute, part of its spring series on security and privacy in historical perspective.

Donohue made a historical—or what legal scholars might refer to as an “originalist”—case against Section 215. She placed it in the context of English and American legal debates about general warrants, tracing the arguments and rulings that led to the Fourth Amendment. A professor at Georgetown University Law School and director of its Center on National Security and the Law, Donohue also holds a PhD in British history from Cambridge University. Her training as a historian was skillfully brought to bear in her talk, which drew a direct connection between 18th century efforts to protect citizens from arbitrary power and current concerns about government overreach in the name of security.

The Fourth Amendment’s prohibition of arbitrary searches and seizures, requiring authorities to obtain a warrant based on probable cause, has its roots in several important English court rulings that went against the Crown in the 1760s, though they drew on legal traditions that harkened back to the 17th century and even the Magna Carta. These precedents entered the colonial American scene in the context of the use of general warrants by customs agents. Upon independence, Virginia and other states prohibited general warrants in their constitutions. The Constitutional Convention of 1787 addressed the issue as well, and the result was the Fourth Amendment.

Donohue’s purpose in tracing this history was two-fold. First, she used it to refute a highly influential 1994 Harvard Law Review article, which argued that the Fourth Amendment does not really require the use of warrants. She made the case that this article, which has been cited in some 40 Supreme Court and appellate court rulings, fails to appreciate the amendment’s historical context and intent. Second, she wanted to show that this long established Anglo-American principle of opposition to general warrants, culminating in the Fourth Amendment, remains not merely relevant, but vital to current debates about where to draw the legal line between national security and personal privacy. If the NSA’s indiscriminate data mining derives its legal sanction from Section 215 of the Patriot Act, then it comprises by any reasonable definition a general warrant, and, as such, is unconstitutional.

I, for one, would dearly love to hear Laura Donohue argue her case before the Supreme Court.

The next lecture in the series Intelligence Services and Civil Liberties: Security and Privacy in Historical Perspective will take place on May 14, 2015, at 6:30 p.m. at the German Historical Institute.

This post first appeared on AHA Today.