Fears about the pervasive reach of our intelligence services soared to unprecedented levels with the recent revelations about the National Security Agency’s massive data collection program, which gobbles up citizens’ phone and internet records in hopes of finding terrorists. In spite of earlier direct denials by officials such as the Director of National Intelligence, James Clapper, we now know that intelligence agents have warrantless access to the personal information of hundreds of millions of Americans.

How much did the Founding Fathers worry about what they called “general warrants,” or broad-based searches not prompted by reasonable evidence of criminal activity? Admittedly, the framers of the Constitution and the Bill of Rights could never have fathomed the technological advances behind cell phones and the internet that have presented the opportunity for such massive technological snooping. Nor could they have envisioned terrorists’ capabilities of wreaking massive death and destruction with weapons ranging from airplanes to nuclear bombs.

Even so, the fear of the arbitrary use of searches, seizures, and arrests, was ever-present among America’s Founders. The dread of this species of government tyranny led ultimately to the adoption of the Fourth Amendment to the Constitution, which states that “the right of the people to be secure in their persons, houses, papers, and effects, against unreasonable searches and seizures, shall not be violated, and no warrants shall issue, but upon probable cause, supported by oath or affirmation, and particularly describing the place to be searched, and the persons or things to be seized.”

A number of early state constitutions and bills of rights also prohibited general warrants and unreasonable searches and seizures, reflecting fears of British investigations and arrests of Patriots during the lead-up to independence. Indeed, a month before the Declaration of Independence was issued in July 1776, the Virginia Declaration of Rights’ 10th section deplored any searches not prompted by compelling evidence, and called general warrants “grievous and oppressive.”

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When the proposed Constitution was framed and sent out for ratification in 1787 (with no Bill of Rights attached yet), the absence of a provision against general warrants caused major concern. A frequently-reprinted editorial by “A Son of Liberty” warned that the unamended Constitution opened the door for citizens to have their property searched, “their private papers seized, and themselves dragged to prison. . .whenever the fear of their lordly masters shall suggest that they are plotting mischief against their arbitrary conduct.”

Patrick Henry, the most influential Antifederalist critic of the Constitution, similarly demanded an amendment that would ban “general warrants to search suspected places, or seize persons not named, without evidence of the commission of fact.” Accordingly, in 1788 Virginia became one of several states to propose a constitutional amendment making citizens secure from unreasonable searches and seizures. Henry and his allies hoped that this amendment (and others) would be added prior to ratification, but he had to settle for trusting James Madison to push the Bill of Rights through the First Congress, which Madison did.

Even if the digital revolution and “big data” were not on the Founders’ horizon, they still laid down basic principles that can help guide us on the NSA controversy. Yes, the Constitution empowered the national government to “provide for the common defense,” and surely one of the government’s key duties today is to discover and disrupt terrorist plots. However, the Founders also knew that any power given (or grabbed) by the government was easily susceptible to abuse.

Few among us would balk at the government energetically pursuing actual terrorist suspects. But the NSA revelations confirm that since 9/11, the American government has become a gargantuan surveillance state with dangerously few limitations. I am confident that NSA operatives are, by and large, really intent on stopping terrorists. But as we see in today’s Middle East, the term “terrorists” can easily morph into a term for one’s political enemies. How much would it take for NSA-style surveillance to turn its focus to journalists (see Fox News’s James Rosen), opposition politicians, advocacy groups, and ordinary citizens who fall out of favor with our all-seeing national government?

Thomas S. Kidd is professor of history at Baylor University and the author of Patrick Henry: First Among Patriots.