safe conduct 
noun [mass noun]
1Immunity from arrest or harm when passing through an area.Despite a guarantee of safe conduct, Nagy was arrested and deported to Romania....
- Despite an apparently ironclad guarantee of safe conduct, he was arrested, imprisoned and burnt at the stake on July 6, 1415.
- Hungary was invaded by troops of the Warsaw Pact on 4 November and, despite guarantees of safe conduct, he was arrested by KGB troops.
Synonyms
freedom of movement, freedom to travel, free access;
immunity
1.1 [count noun] A document securing a person’s safe conduct.Access to work and ration cards meant getting identity cards and safe conducts which involved certificates of ‘good behaviour’ from local Falangist officials and parish priests....
- They were given safe conducts though inevitably numbers were set upon and robbed.
- These took the form of a safe conduct pass signed by a senior commander.
Synonyms
(travel) permit, pass, passport, transit visa, authority, authorization, credentials;
French laissez-passer