I'm unsure of the legal side here but in the UK the police are required to provide proof of where the evidence came from and it's provenance for it to be admiss

I'm unsure of the legal side here but in the UK the police are required to provide proof of where the evidence came from and it's provenance for it to be admissible in court. This can mean the person in control of the evidence becoming a witness to speak in court to the veracity of the of the evidence, especially if only a copy was taken from the owner so as not to leave the owner without the original thing (ie, a phone used to record something).