Senior advisor Harold Koh penned a memo to the State Department Saturday, tenuring his resignation and detailing why. Koh has been the sole political appointee for the State’s legal team. Politico obtained and subsequently leaked his memo.

Particularly, Koh claimed he left over Title 42, a Center for Disease Control and Prevention health order. The order is invoked in the name of border security, since it suspends the right to introduce certain persons during a pandemic.

“When the Trump Administration first issued its Title 42 order in March 2020 in response to the growing COVID crisis, it was the first time the CDC had invoked its authority under this statute,” Koh wrote. “But the breadth and subsequent implementation of Title 42 authority now raises significant concerns about whether the United States is living up to its binding obligations under international law.”

Remarkably, Koh even called out Biden’s hypocrisy. When photos of Border Patrol agents wrangling Haitian migrants on horses went viral, Biden condemned the agents. “It’s wrong,” Biden said at the time. “It sends the wrong message around the world and sends the wrong message at home. It’s simply not who we are.”

“The same could be said of current illegal and inhumane policy of Title 42 expulsions,” Koh wrote. “It simply is not worthy of this Administration that I so strongly support.”

Meanwhile, Department of Homeland Security Secretary Alejandro Mayorkas insists that Biden cannot undo the order. “The pandemic is not yet behind us,” he said back in May. Then, he claimed its “tied to data.” Therefore, an executive decision could not alter it.

Now, Koh will still work as a consultant to the State while taking on a new role at Oxford University.

You can follow Jenny Goldsberry on Twitter @jennyjournalism.