A British court ruled Thursday that a U.K. government plan to send asylum-seekers on a one-way trip to Rwanda is unlawful, delivering a blow to the Conservative administration’s pledge to stop migrants making risky journeys across the English Channel.

Refugee law expert David Cantor said the ruling would “send a ripple effect more widely through this idea of sending asylum seekers to third countries.”

“Any country that might wish to enter into this kind of memorandum with the U.K. government, as Rwanda did, would equally be quite likely to be a government which had weak asylum procedures, (where) there were questions about safety in the country,” said Cantor, director of the Refugee Law Initiative at the University of London’s School of Advanced Study.

He said the U.K. “has had negotiations with many countries which do have robust court structures and asylum procedures, and there’s very little willingness there to contemplate these sorts of schemes.”