With President Trump and congressional Democrats still at odds over funding a southern border wall, the president continues to float the possibility of declaring a national emergency to secure money for it, a proposition of questionable legality that would almost certainly end up in court.

But even if Trump survives a court challenge, there’s another legal hurdle he would have to face: eminent domain.

The Washington Post’s Matt Viser reports:

There are complications to building a wall along the Texas border. The topography is challenging. A river adds additional issues. And unlike in Arizona and New Mexico, most of the land along the Texas border is privately owned, so building any structure would require taking it by eminent domain.

Litigation is still pending on behalf of some of those from whom land was taken after President George W. Bush signed the Secure Fence Act in 2006.

In hours of media appearances over the past three years reviewed by The Fix, highlights of which you can watch in the video above, Trump took an expansive view of the government’s ability to seize private land via eminent domain, calling it “necessary” for the country.

In a February 2016 appearance on Breitbart News Daily, Trump previewed how he might use eminent domain in the White House.

“We are going to need a little eminent domain to get that wall built, just so you understand,” Trump told Stephen K. Bannon at the time. “You know, you need eminent domain. You have to take certain areas, okay? I hate to tell you.”

Now amid one of the longest government shutdowns in history, Trump is considering declaring a national emergency not only to re-appropriate money for his wall but also to potentially expand the government’s eminent domain powers.

“Under the military version of eminent domain and under actually homeland security, we can do [eminent domain] before we even start,” Trump said Friday. “Eminent domain is something that has to be used, usually you would say for anything that’s long, like a road, like a pipeline or like a wall, or a fence.”