French police have wide powers of search and seizure and can ask you to prove your identity at any time – whether or not there is 'probable cause'.
Foreigners must be able to prove their legal status in France (eg with a passport, visa or residency permit) without delay.
If the police stop you for any reason, be polite and remain calm. Verbally (and of course physically) abusing a police officer can lead to a hefty fine, and even imprisonment.
You may refuse to sign a police statement, and have the right to ask for a copy.
People who are arrested are considered innocent until proven guilty, but can be held in custody until trial.
Drugs & Alcohol
French law does not distinguish between 'hard' and 'soft' drugs.
The penalty for any personal use of stupéfiants (including cannabis, amphetamines, ecstasy and heroin) can be a one-year jail sentence and a €3750 fine but, depending on the circumstances, it might be anything from a stern word to a compulsory rehab program.
Importing, possessing, selling or buying drugs can get you up to 10 years in prison and a fine of up to €500,000.
Police have been known to search chartered coaches, cars and train passengers for drugs just because they're coming from Amsterdam.
Ivresse (drunkenness) in public is punishable by a fine.