School: Evidence final coming up
The law of evidence is a strange and wonderful world that applies in both civil and criminal trials. The first concept that most evidence courses begin with is hearsay. It's a simple notion, really - that out-of-court statements cannot be used to prove what they assert. The tough thing is that there are so many darn exceptions to the rule.
Here's a fun video showing some of the exceptions to hearsay (audio level's a bit low):