That means to paralyze.

For example: Bauernproteste legen Städte und Autobahnen lahm means farmers’ protests paralyze cities and freeways.

The week of rage – What’s in store for us tomorrow?

Starting tomorrow, farmers all over Germany will be taking to the barricades to demonstrate against the government’s (subvention-cutting) policy. Expected are highway blockades, rallies, protest camps and rallies all over the country. The farmers’ association expects “tens of thousands of tractors” to take part.