Under the EIO Directive : Besides the grounds of non-recognition/execution provided under art. 11 Directive 2014/41/EU, recognition and execution might be refused where the execution of the covert investigation would not be authorised in a similar domestic case or if it was not possible to reach an agreement on the arrangements for the covert investigations, i.e. duration, detailed conditions, legal status of the officers concerned.
Under MLA instruments : To be requested by international letters rogatory. Contents: an indication of the authority making the request; a summary of the facts; an indication of the criminal conduct under investigation; the object of and the reason for the request; precise information for the purpose of identifying the criminal environment to be infiltrated ; and the desired duration of the infiltration. Execution of the measure in conformity with the procedure applicable in the requesting State : possible as a matter of principle; to be assessed on a case by case basis. Relevant formalities to be expressly indicated.
Irrespective of the statutory basis: duration limited by law to a maximum of four months; prolongation possible on four months’ basis as long as necessary. Outcome of the measure to be put down in a written report.
Assistance or participation of agents of the requesting State in the execution of the measure: Possible as a matter of principle, to be assessed on a case by case basis.