"Now, police must at least get a magistrate to rubber-stamp such spying warrants."
Scotland doesn't have magistrates, except in Glasgow. It could presumably be approved by a Justice of the Peace or a Sheriff. Glasgow magistrates are slightly more senior than Justices of the Peace. Sheriffs in Scotland are a type of judge, not a police chief as in the US, and much more senior.
Unless, maybe you mean a Magistrate in Glasgow, a Sheriff elsewhere?