A senior adviser on the State Department’s legal team who is stepping back from his role as he takes a new job at Oxford University has issued a sharp rebuke of President Joe Biden’s use of a Trump-era policy to expel migrants. Harold Koh asserted in an Oct. 2 memo that Title 42 was “illegal” and “inhumane” and “not worthy” of the administration he said he strongly supports. In spite of a decision to step back from the politically appointed position, Koh will stay on in a consulting capacity, Politico reported.

“I believe this Administration’s current implementation of the Title 42 authority continues to violate our legal obligation not to expel or return (‘refouler’) individuals who fear persecution, death, or torture, especially migrants fleeing from Haiti,” the memo states. The Biden administration’s continued use of Title 42 to boot thousands of migrants without letting them seek asylum has been widely criticized. Meanwhile, administration officials have contended that Title 42 has been used amid public health concerns raised by the Centers for Disease Control and Prevention. Koh insisted in the memo that “lawful, more humane alternatives plainly exist.”