Streaming-service subscribers—and their friends and families—got a jolt this summer. Soon news stories reported that the decision could also apply to subscribers who share, say, their Netflix passwords—which would make roughly half of all streaming-service subscribers guilty of a federal crime. But the major providers have been slow to curb the practice, although some have made changes to control the number of devices that can be used for a single account or the number of videos users can stream at the same time. For example, most companies use the word household without defining it, leaving users to guess whether their household includes, say, a kid who is away at college or Grandma who lives in the apartment downstairs—not to mention a group of un-related roommates. That ambiguity leaves the door open for companies to change their currently lax policies and crack down on account sharing.