It is true that 9/11 changed America.

The heart of that change is how the terrorists broke Congress.

The branch of government that is closest to the American people, most sensitive to their opinions and the first stop for any citizen protest against violations of constitutional rights, has been irrevocably weakened. And, tragically, that means American democracy has been weakened.

Within weeks of the attacks, Congress began to willingly surrender its power as a check on the power of the president to violate the privacy of Americans, start wars, set policy on national security, jail terror suspects without any legal safeguard, send suspects to jails in other countries and even have U.S. agents torture people.

This drain of Congress’s authority began with a power grab by the Bush administration as it aggressively claimed every tool to prevent another attack. There was nothing wrong with that. But 10 years later, even as the White House shifted from a Republican to a Democratic president, Congress never once resisted this diminution of its power.

The key moment for this change was the Patriot Act — passed by Congress just six weeks after Sept. 11, 2001. A mere 66 members of the House and one member of the Senate voted against it. This legislation gave the executive branch broad, unprecedented power to conduct surveillance of, and detain, American citizens in the name of preventing terrorism.

In 2005, then-Sen. Barack Obama wrote to his Senate colleagues arguing against the law’s roving wiretap provision, calling it “a sweeping power never authorized in any context by Congress before the Patriot Act.”

In May of this year, President Obama signed a four-year extension of key parts of the law, including provisions that allow for those same roving wiretaps and government access to citizens’ library records. Privacy advocates and civil libertarians have tried relentlessly to repeal and limit the legislation.

Then there was the creation of the Department of Homeland Security in 2002, the third-largest Cabinet-level department after Defense and Veterans Affairs. It merged dozens of agencies into one central bureaucracy with a budget of more than $55 billion last year. It is easy to forget it did not exist 10 years ago.

And there is the continuing use of the military detention facility in Guantanamo Bay, Cuba, where terrorism suspects are held outside the parameters of U.S. law. Despite campaigning on a promise to close it, Obama has kept it open. He has also continued the Bush practice of trying terror suspects before special military commissions.

The handling of terror suspects also includes the Bush administration’s use of such enhanced interrogation techniques as water boarding. As former Vice President Dick Cheney reminds us in his new memoir, the executive branch authorized this program with only nominal consultation with Congress.

Perhaps in no area has the power drain been more consequential than in the wars in Afghanistan and Iraq. Obama escalated these wars with the acquiescence of Congress.

No president has endorsed the War Powers Resolution of 1973. It prevents the president from committing U.S. troops to armed conflict without the consent of Congress. Congress has not issued a formal declaration of war since World War II. Instead, “authorizations of military force” have become a convenient substitute. Only one member of Congress voted against the initial resolution to send troops to Afghanistan, while 166 House members and 23 senators voted against a similar one authorizing the war in Iraq.

The U.S. involvement in Libya has set a precedent wherein Congress takes an even more diminished role.

When asked about Libya, Matthew Waxman, an expert on national-security law at Columbia University Law School, said, “The constitutional lines defining the president’s authority to use military force without congressional authority have never been clearly defined and remain subject to substantial debate.”

Rep. Walter Jones (R-N.C.) tried unsuccessfully to restore some of the war powers to Congress in 2007. His aim was to prevent the Bush administration from launching a pre-emptive military strike against Iran — still a plausible scenario.

As we begin the second decade of the post-9/11 world, I resolve to speak more about the diminished role of Congress in setting national security policy. This is an issue that has been largely confined to constitutional law symposia but it is time for everyone, including the press, to start speaking up loudly.

Take a look at the enumerated power of Congress in Article I of the Constitution. It is clear that the framers intended Congress to have more power than the president in setting policy for national security.

All of the candidates for president should be asked what their views are on this subject. Anyone running for Congress should be asked about it. Nominees to sit on any federal court should be questioned on this issue.

It is simply too dangerous to place this much power in the hands of one person in these dangerous times — even if that person is the president of the United States.

Juan Williams is a writer, author and Fox News political analyst. His next book is "Muzzled: The Assault On Honest Debate" (Crown/Random House) was released in July.