Germany’s top court has ruled that police can use spy software to monitor phones and computers only in cases involving serious crimes, Reuters reported.

The court found a 2017 law too broad, warning it could impact people who aren’t under suspicion. It said that surveillance of encrypted chats and devices is a serious intrusion and must be strictly limited.

Investigations into lesser crimes—those carrying a maximum sentence of three years—can no longer involve such monitoring. While parts of the law remain temporarily in effect, they must be revised to meet constitutional standards, according to Reuters.