The next step backwards: Berlin has a new law prohibiting landlords from demanding rents that are more than 10 percent higher than the area average, in an attempt to keep housing affordable in a city that’s attracting 50,000 new residents a year. The rule relies on a disputed index — known as the Mietspiegel — that critics say is a statistical crapshoot.

“The rent brake is essentially a transfer of wealth from landlords to tenants. Berlin will become less of a destination for international investors because capital doesn’t like to be constrained.”