Each use of a 'real-time' remote biometric identification system in publicly accessible spaces for the purpose of law enforcement should be subject to an express and specific authorisation by a judicial authority or by an independent administrative authority whose decision is binding of a Member State. Such authorisation should, in principle, be obtained prior to the use of the AI system with a view to identifying a person or persons. Exceptions to that rule should be allowed in duly justified situations on grounds of urgency, namely in situations where the need to use the systems concerned is such as to make it effectively and objectively impossible to obtain an authorisation before commencing the use of the AI system. In such situations of urgency, the use of the AI system should be restricted to the absolute minimum necessary and be subject to appropriate safeguards and conditions, as determined in national law and specified in the context of each individual urgent use case by the law enforcement authority itself. In addition, the law enforcement authority should in such situations request such authorisation while providing the reasons for not having been able to request it earlier, without undue delay and at the latest within 24 hours. If such authorisation is rejected, the use of real-time biometric identification systems linked to that authorisation should cease with immediate effect and all the data, as well as the results and outputs of that use should be immediately discarded and deleted. Such data, results and outputs include all data, results and outputs linked to a use of such system developed in the course of the law enforcement activity in question. It should not extend to input that is lawfully acquired in accordance with another national or Union law. In any case, no decision that produces an adverse legal effect on a person may be taken based solely on the output of the 'real-time' remote biometric identification system.