Article L3115-4 of the French Public Health Code
In the event of a risk to public health, within the meaning of Article 1 of the 2005 International Health Regulations, identified on board a means of transport, within the meaning of the same article, the representative of the State in the département shall take the necessary measures to combat the international spread of disease. He may in particular: 1° Prohibit free circulation or immobilise the means of transport pending…