It's not, but depending on the country not every judicial system has the same weird regulations as the US one. For example hearsay, evidence without a clear chain of custody, and many other things that would be thrown out of a US court are accepted in most other western countries. The Judges know how to deal with that evidence and under which circumstances except it or not, some one lost a tag on an evidence bag doesn't really scares them, the evidence came from an "unofficial" source, as long as it's credible they'll take it in and so on.