What Donald Trump doesn’t want you to know about his plan to build a “Great Wall” between the U.S. and Mexico: He’d need to steal private property from Americans to build it.

In 2013, the federal government succeeded in using eminent domain to acquire the land rights to build a border fence across Dr. Eloisa G. Tamez’s ancestral home in 2013. Dr. Tamez’s land has been in her family since the King of Spain granted it to them in 1767. But it rests on the U.S.-Mexican border, so the Department of Homeland Security took it to erect a border wall under a federal law enacted during the Bush Administration.

The Great Wall of Trump would mean hundreds, if not thousands, of Tamezes.

In the words of the Donald, the border is “2,000 miles, but we really need 1,000 miles” of wall. The thousand-mile disparity suggests that Trump would incorporate existing walls and natural boundaries. In 2006, Congress passed the Secure Fence Act, calling for no less than 700 miles (and no less) to be constructed on vulnerable points of the 1,954 mile U.S.-Mexico border. Completed segments of that project plus natural boundaries could reasonably make it so only 1,000 miles of actual wall building is necessary.

Yet, in carrying out Congress’ 2006 wall construction mandate, the Department of Homeland Security hit a snag: “real estate issues” were “causing significant delay,” according to its Inspector General. And that makes perfect sense — recall Dr. Tamez. Her condemnation case, instigated in 2008, only closed last year, a few days shy of seven years.

The Government Accountability Office reports that “federal and tribal lands make up 632 miles, or approximately 33 percent, of the nearly 2,000 total border miles.” What of the remaining 66 percent? “Private and state-owned lands constitute the remaining 67 percent of the border, most of which is located in Texas.”

That means that if Trump’s plan to build another 1,000 miles of wall is carried to fruition, thousands more homeowners will see their property destroyed or partially walled-off.

Indeed, during construction of the “Secure Fence” in 2008, to actually finish the 370 miles of pedestrian fencing that Homeland Security planned, required “negotiating purchases and voluntary sales from more than 480 landowners” and “filing condemnation cases” where those negotiations broke down, again according to Department of Homeland Security’s Inspector General, whose report dryly notes that “acquiring real property from non-federal owners is a costly, timeconsuming process requiring negotiations and sometimes condemnation.”

If the first 700 miles built in from Bush-era mandates took over a decade to litigate eminent domain cases like Dr. Tamez’s and affected nearly 500 homeowners, Trump’s 35-foot-tall-1,000-mile-long monstrosity will take at least as many. The federal government used a good portion of its land already in the Bush-era construction. The fence built so far extends to Texas, which means it mostly covers land that was already federally owned. Trump’s new fencing would be built primarily on state-owned and private lands.

So Trump, who has a long history of using eminent domain to his benefit as a private citizen, intends to use it as President to take land from American property owners.

Eminent domain is certainly contemplated by the Constitution. But under the Fifth Amendment, the federal government would be on the hook for providing “just compensation” to all of these property owners. That will be quite expensive for the taxpayer, to say the least.

Moreover, there is gross impropriety in taking hundreds of people’s land—including Native American burial grounds where construction pursuant to the Secure Fence Act already has left human remains hanging off of the machinery used to build the wall, even as that wall is widely recognized as an ineffective solution to immigration and drug trade issues.

America deserves better than half-baked notions about futile Great Walls that will only result in decades of condemnation proceedings and pain for American homeowners and taxpayers. One can only pray that Trump supporters will eventually care about these issues and hold their leader responsible for specific, reasonable plans.

Randal John Meyer is a legal associate at the Cato Institute and a graduate of Brooklyn Law School. Send comments to [email protected].