https://www.vice.com/en_us/article/7k9z7x/encrochat-hack-illegal-defense-nca

Law enforcement's hack of Encrochat, an encrypted phone network used heavily by organized crime, is now facing a wave of legal challenges across the United Kingdom as defendants raise issues with the mass hack.

Many of the legal challenges are awaiting the results of one case in particular, which will rule whether message content gathered by law enforcement's malware from user's Encrochat phones is admissible in court. That hearing, scheduled for the end of this month, will  potentially throw the prosecutions of alleged serious criminals into doubt.