On New Year's Eve, President Obama signed into law a bill that eliminates one of the fundamental protections of the U.S. Constitution:

The right for people not to be detained indefinitely by the government without being formally convicted of crimes.

This erosion of the Constitution, which came in the form of new language in the annual National Defense Authorization Act (NDAA), allows the government to hold anyone suspected of being associated with terrorism indefinitely, without any form of due process.

No indictment.

No judge or jury.

No evidence.

No trial.

Just an indefinite jail sentence.

In other words:

If someone in the government suspects that you're somehow associated with terrorism, you can be jailed indefinitely in a military prison.

Defenders of this language — including Senators John McCain (R) and Carl Lavin (D), who sponsored it — position it as being tough on terrorism.

And that's fine: Everyone wants to be tough on terrorism.

There are ways of being tough on terrorism that preserve basic rights. Unfortunately, this isn't one of them.

If the government and military never made mistakes--if they never suspected people of being associated with terrorism who aren't actually associated with terrorism--then this language wouldn't be so scary.

But, like anyone else, governments and armed-forces personnel do make mistakes.

Frequently.

So removing the intelligent and reasonable requirement that government suspicions be subjected to due process is frightening.

Of course, in signing the bill, President Obama promised that he would never use it to detain Americans.

While that's comforting, other Presidents may not feel compelled to honor that promise. And human-rights activists who don't believe that basic human rights apply only to American citizens are justifiably upset that America can now detain anyone indefinitely without due process.

(And, by the way, the common pushback that the bill cannot be used to detain Americans is a crock. The bill clearly states that Americans are not "required" to be detained indefinitely. Not being "required" to do something, and "preventing" something are quite different.)

To be clear: This bill isn't just tough on terrorism. It overturns a key part of the Constitution. And it presumes that those who serve in the government and military are always omniscient and perfect and will always use their power for the good of all citizens.

And that presumption, as everyone who has ever watched our government in action knows, is laughable.

Will America be transformed into a brutal police-state by this one bill? Probably not. But the constitutional protections and other checks-and-balances that separate democracies from authoritarian states are rarely eliminated in one fell swoop.

Rather, theses protections are eliminated gradually, by governments and rulers who incrementally grant themselves ever more power.

Taken individually, each incremental change may seem well-meaning and justifiable.

But, gradually, the checks-and-balances that form the basis of a fair society are eliminated.

In signing the NDAA bill, President Obama was presumably yielding to political expediency. The bill, after all, had military funding attached.

But that's no excuse.

The Presidential veto is supposed to function as a critical check-and-balance in our system, to be invoked when Congress collectively goes insane.

And this is one bill that Obama should have vetoed.

SEE ALSO: This Is The Section Of The NDAA That Is Freaking People Out