Enjoying a bottle of wine with friends on the banks of the Seine has long been one of the joys of living in France. No container laws here! But alas, oui, there actually are laws banning the consumption of alcohol in public. Up until now, the French police have simply turned a blind eye to the obvious open bottles (and beer cans) enjoyed by the picnic crowds, as long as everyone is well-behaved. And therein lies the problem.
Some people just don't know how to behave, and it's been getting worse (with about two dozen arrests on the Champ de Mars this week as French teens celebrate end of exams with a bit too much exuberance and destruction of public property). If you've ever seen the Champ de Mars in the morning, you'd understand. It's covered in bottles, cans, cigarette butts, garbage, and broken glass. Not nice.
Alcohol (and any glass containers) have long been banned in public parks, but now the police are openly enforcing the laws by either confiscating or pouring out any alcoholic beverages being consumed in the wrong place at the wrong time.
This is where it gets confusing.
The ban is not everywhere in Paris, and it's not a 24-hour ban. For example, open containers are not allowed on the Champ de Mars between 4pm and 7am. So you can drink there for your lunch picnic, but you won't be drinking there for the Bastille Day fireworks show (well, not legally, anyway).
Drinking on the street is banned after 9pm in several other neighborhoods including the Champs-Elysées, the Parvis Notre-Dame, all parks and gardens, Beaubourg, les Halles, the Marais, the Latin Quarter, rue du Faubourg Montmartre, Pigalle, the Canal Saint-Martin, Bastille, Oberkampf, and all train stations. The minimum fines are 38 euros, up to 750 euros.
If you're not sure, just don't drink after 4pm in any public places (or risk having to dump it out quickly if you see police handing out fines). And if you do picnic, remember to clean up after yourselves and encourage others to do the same.
Read more about the Paris drinking laws here (in French).