> How many matches will US judges require before they sign warrants for arrests, search and seizure of digital devices? If they are technically competent it shouldn't only be 1, but I don't trust all judges to understand probability well enough to require multiple matches.

Even that doesn't come without issue. How long before '1' becomes the value, because, say for example the number is ten, there's also a horrendous PR spin of "Apple has a high degree of suspicion that you have CSAM on your device, but since there's only 8 images, they won't do anything about it" - "Apple allows up to X non-reported CSAM images on Apple devices" is hard to represent in any positive fashion.