An increasing number of railway incidents has led to "open-container" bans on alcohol in Germany's train stations and on the train platforms. Stations in Kiel, Braunschweig, and Berlin - Berlin Hbf station, and Berlin Gesundbrunnen - will come first, starting in September, with the other 5400 or so German train stations following suit after that.
Note that restaurants/bars within the stations are not affected by this new policy.
There have been some "last-straw" incidents in which railway employees have been attacked - including one death. As of now, however, the ban will apply only to the stations and platforms themselves, not on the trains, which is a little surprising since the employee who died was hurled from a train.
Personally, I think this is a good move. Not that I've seen any violence there myself, but the rise in loitering in the stations I've noticed, along with the rowdy behavior of soccer fans on game days, have been a cause for concern and often involve some folks who are actively drinking or obviously inebriated. I would guess that increased ridership as a result of the dirt-cheap Deutschland Ticket and the recent heat waves might be contributing factors as well, but "na, ja", you can't legislate the weather.
Still, I would be pretty unhappy if they end up extending the ban to passengers on the trains, a possibility that some of the authorities are calling for. Enjoying an adult beverage like an adult always makes for a more enjoyable journey,