Privacy is a fundamental right that belongs to each and every one of us. Governments aren’t allowed to violate it whenever it pleases them. If the authorities want to spy on someone, they should need to get permission to do so.
The European Court of Human Rights has brought a decision of key concern to the collection of data in Europe. The ECHR has declared that the mass surveillance by the United Kingdom violated the rights to privacy and family life.
Why? Because it's useless and it's dangerous. Only traditional methods of gathering intelligence have helped security services stop terrorism. Mass surveillance, which doesn't produce results, is draining resources away from tools that actually work.