The latest in my ‘Learn Something New Every Day’ series – taken from The Great Courses’ “Trails of Evidence: How Forensic Science Works” (Lecture 30: When forensics are on trial)
As well as probative and relevant (see yesterday’s post), evidence must be deemed competent (ie: not prejudiced, not un-constitutional, not privileged, not hearsay) in order to be admissible in court.
- Excessive Prejudice Any evidence that is likely to excessively prejudice a judge/jury is not admissible (past convictions, bad character). Also includes evidence that might seriously offend the sensibilities of the general public or the jury (very gruesome pictures etc),
- Fruits of the Poisoned Tree When a warrant is issued by a justice authority under the terms of the US Constitution, it is highly specified to an address, the specific evidence being sought and the people being searched. If investigators are looking (under the warrant) for blood-stained clothing and they find a head in the fridge, the head cannot be used as evidence.
- Under Privilege Conversations between a suspect and their lawyer, psychiatrist, priest or doctor are protected under law. In the US spousal privilege protects a spouse from having to (or being able to) testify against each other.
- Hearsay In legal terms, ‘hearsay’ is potential evidence said or written outside the court that attorneys try and present in court as ‘truth’. (eg: If you hear someone confess a crime you can testify to say what you heard but you cannot present it as a truth.) Forensic reports are the ultimate hearsay (the scientist can testify to the results they got but not to whether or not those results are ‘truth’) but they are deemed an exception to hearsay.