Hillary Rodham Clinton voted as Senator for the USA PATRIOT Act in 2001 and 2006, and Donald Trump has approved its renewal, saying he tends to "err on the side of security."

In the Democratic debates, Clinton harshly criticized NSA whistleblower Edward Snowden, insisting, probably wrongly, that he "could have gotten all of the protections of being a whistleblower" and "raised all the issues" without breaking the law. Trump has called Snowden a traitor, promised to get Russian president Vladimir Putin to hand him over, and in the past even suggested him worthy of execution.

Both candidates want to expand foreign intelligence. Clinton recently told Fox television host Bill O'Reilly that among her "priorities is to launch an intelligence surge" and more information-sharing to combat terror. Trump told CBS journalist Leslie Stahl that, to defeat ISIS, "we're going to have unbelievable intelligence, which we need [and] right now, we don't have."

Both major political parties have nominated surveillance hawks for the highest office in 2016, but we could excuse the public for discerning partisan differences. In recent years, both sides have postured as disagreeing fundamentally. Barack Obama ran for president echoing fellow Democrats' condemnation of President George W. Bush's attempts to immunize telecoms implicated in NSA warrantless wiretapping.

Under Obama's presidency, the Republican National Committee denounced the NSA's "dragnet program" as likely "the largest surveillance effort ever launched by a democratic government against its own citizens" and its mass data collection as "contrary to the right of privacy protected by the Fourth Amendment."

Inconsistent politicians have mirrored a shift among constituents. The Pew Research Center in 2006 found that 37 percent of Democrats and 75 percent of Republicans considered Bush's surveillance program acceptable. In 2013, 64 percent of Democrats and 52 percent of Republicans approved NSA surveillance under Obama.

As far back as we can trace the American surveillance state, its defenders and detractors have transcended any consistent partisan divide. Republican president Theodore Roosevelt created what became the Federal Bureau of Investigation, against warnings from both parties. Democrat Woodrow Wilson oversaw a massive expansion of foreign and domestic intelligence during World War I. For forty-eight years, J. Edgar Hoover's FBI conducted spying on behalf of both parties' presidents, who were often eager for his assistance targeting political enemies. Both Republicans and Democrats targeted foreigners, allies, the far right, and the radical left.

Those seeking to understand surveillance must look beyond politics and into policy. Foreign policy in particular has a profound if fraught relationship to surveillance abroad and at home. A bipartisan foreign intelligence posture has tended to bleed into the domestic sphere. From the Progressive Era through the Cold War, fears of a fifth column under foreign influence, and tactics first used in foreign occupations, inspired application of surveillance techniques within the United States. More pedestrian policy goals, such as wars on crime, drugs, and poverty, have also fueled violations of privacy.

Even as policy dynamics transcend partisanship, the legal principles at stake are frustratingly complex. Both principled and partisan critics accuse their opponents in power of unambiguously violating the Constitution, whereas both Bush and Obama claimed their surveillance program passed the Fourth Amendment test.

Civil libertarians find such defenses absurd, but the Fourth Amendment is no privacy panacea. It always accommodated vast search powers. Wiretapping wasn't even covered until 1967, when the Court found a Constitutional "right to privacy" beyond a physical property right. Conservatives long skeptical of such a "right to privacy" lack an originalist argument for why NSA surveillance violates the Fourth Amendment. Generally speaking, modern technology and the terror war's global battleground have revealed the limits of simple legal arguments.

If there is no consistent Fourth Amendment principle against the surveillance state, how could we expect a consistently pro–Fourth Amendment political party?

Granted, third parties, like the Libertarians and Greens, have more relentlessly criticized surveillance powers and are much more favorable toward Snowden. It is also outside mainstream electoral politics that we find any fundamental rethinking of the policy priorities that drive the surveillance state at home. This might discourage those who want Fourth Amendment restoration in the next election. But to understand the deeper issues requires more than partisan grandstanding.

Politics cannot begin to touch a surveillance power so entrenched and a privacy right so elusive. Privacy advocates must look to policy prescriptions, foreign policy history, and broader cultural values.

Anthony Gregory is a research fellow at the Independent Institute and author of the new book American Surveillance: Intelligence, Privacy, and the Fourth Amendment (University of Wisconsin Press for the Independent Institute). Thinking of submitting an op-ed to the Washington Examiner? Be sure to read our guidelines on submissions.