Berlin’s Airbnb Crackdown Is Now Underway by David Meyer @FortuneMagazine May 2, 2016, 6:09 AM EDT E-mail Tweet Facebook Linkedin Share icons Berlin has started enforcing its (deep breath) Zweckentfremdungsverbot after a two-year transition period. This is a ban on “misusing private property,” such as by renting apartments to tourists without permission, and it has big implications for hosts on platforms such as Airbnb. Days before the enforcement period began on May 1, Airbnb removed hundreds of listings for the German capital, with the number of listings dropping around 40 percent in a month. Berlin has a housing crisis, and rents went up by more than half between 2009 and 2014. The problem predates the current influx of refugees, but that is obviously making housing even more of a concern. Get Data Sheet, Fortune’s technology newsletter. Andreas Geisel, the Berlin senator in charge of urban development, sees the new law as a way to return “misappropriated” apartments to Berliners and newcomers. The Zweckentfremdungsverbot still allows people to rent out rooms, but not whole flats. Transgressors face fines of up to €100,000 ($115,000) and the city authorities are urging neighbors to let them know if they think the rules are being broken. There’s a good chance that people will do that. Housing shortage aside, these short-term lets often prove popular with people visiting the city for a party (and this is a party town). In quiet apartment blocks, this can be annoying to say the least — something people also complain about in cities such as Barcelona. Local rivals to Airbnb are not happy about the ban — Wimdu has sued the city authorities — and Airbnb itself is complaining that the ban will hurt those Berliners who rely on Airbnb rentals for their living.