When the police pounded the door before dawn at a home in north-west Germany, a bleary-eyed young man in his boxer shorts answered. The officers asked for his father, who was at work. They told him that his 51-year-old father was accused of violating laws against online hate speech, insults and misinformation.

He had shared an image on Facebook with an inflammatory statement about immigration falsely attributed to a German politician. "Just because someone rapes, robs or is a serious criminal is not a reason for deportation," the fake remark said. The police then scoured the home for about 30 minutes, seizing a laptop and tablet as evidence, prosecutors said.