I am not a lawyer, so if anyone has legal expertise please correct me, but I do not think lack of chain of custody is at all a reason to exclude any form of evi

I am not a lawyer, so if anyone has legal expertise please correct me, but I do not think lack of chain of custody is at all a reason to exclude any form of evidence. Now, what it does do is provide an opening for arguments that that evidence has been tampered with. That claim must then be dealt with, but there are ways of doing that. There are experts that are precisely employed to determine to a high degree of accuracy (though not certainy) whether such things have been modified since their point of creation. Moreover, the exisence of a chain of custody does not absolutely prove it was not tampered with, it can certainly help in that you know who was accountable if it was modified at certain points of time but that is not the same.