A French scientist was denied entry into the United States and deported after U.S. immigration officers reportedly found private messages on his phone criticizing President Donald Trump’s science policies. The incident has triggered diplomatic tension between France and the United States and reignited international concern over academic freedom under the Trump regime.

The researcher, whose name has not been released, was affiliated with the French National Centre for Scientific Research (CNRS) and had arrived in Houston on March 9 to attend a scientific conference. Upon arrival, he was detained by Customs and Border Protection (CBP) and subjected to an electronic device search. During the inspection, CBP officers allegedly cited personal messages that criticized Trump’s handling of climate policy and U.S. research funding.

The scientist was denied entry and put on a return flight to France the following day, despite holding a valid visa and having no prior issues with U.S. immigration. The Department of Homeland Security has declined to comment on the case, citing privacy rules, but maintained that CBP reserves the right to refuse entry based on national interest.

France’s Minister for Higher Education and Research, Philippe Baptiste, condemned the deportation, saying it appeared to be “politically motivated retaliation” and a direct affront to scientific freedom. “Private criticism of a foreign government’s policy is not a crime. This action sends a dangerous message to the global academic community,” he said.

The case adds to a growing list of incidents in which foreign nationals have been detained, interrogated, or denied entry under Trump’s second term, particularly in contexts involving dissent or political critique. Academic institutions and human rights organizations warn this trend mirrors McCarthy-era blacklisting tactics, with wide-reaching consequences for scientific collaboration and free expression.

Reported by Casey Clearview for The Crustian Daily.