USA Today recently published my op ed on the potential dangers of using emergency powers to build Donald Trump's border wall—an option he may yet resort to if Congress continues to deny him the funding he seeks. Here is an excerpt:

President Donald Trump recently said that he will "almost… definitely" resort to emergency powers to build a wall on the Mexican border if Congress does not give in to his demands. That may be his way out of this government shutdown if Democrats, unmoved so far by his televised address Saturday, continue to hold the line. But it should not get him that wall.

In order to build it, he would need not only funds, but also the power to seize property from unwilling owners through the use of eminent domain. Allowing him to do so would set a dangerous precedent and threaten the property rights of thousands of Americans…..

Even if he can declare a "national emergency," however, that does not mean he can use it to pay for and build a wall….

Even if the president can use emergency powers to get funds, that does not mean he can seize property by eminent domain. The Supreme Court has long held that the use of eminent domain must be "expressly authorized" by law. No emergency laws "expressly" permit the use of eminent domain for border walls not otherwise authorized by Congress.

Building Trump's wall requires using eminent domain on a massive scale. Less than one-third of the needed land is currently owned by the federal government. The rest would have to be taken from private owners, Native American tribes, and state governments, many of whom are unlikely to sell voluntarily.

The result would be one of the largest federal condemnations in modern American history…. Construction and legal battles over compensation can drag on for years.

This reality underscores the absurdity of claiming that a wall is needed to combat an "emergency." Emergency powers are intended to address immediate threats that cannot be dealt with by slow-moving legislative processes. If the supposed emergency can be fixed by a wall that takes years to build, that means it was not an emergency in the first place….

If Trump succeeds in using emergency powers to build the wall and seize property through eminent domain, future presidents could exploit this dangerous precedent. They too could declare a "national emergency," and then divert military funds and take private property without congressional authorization.