That is a reasonable question. Evidence is the type of thing that most people have some idea of what it is, but not exactly. So, let’s first describe what it actually is, then what it may look like.
The first thing to remember is that evidence is a legal matter. That is, evidence for the purpose of forensics will be collected and preserved and analyzed in the furtherance of the investigation at a crime scene. The term “crime” meaning someone may be criminally charged, and ultimately face incarceration. If you slip on a banana peel at your favorite convenience store, the banana peel may be considered evidence, but will only be used in a civil trial. “Civil” means that there will only be monetary damages awarded – no one is going to jail. Unless of course, they find a mad serial banana peel placer going around town putting them at many locations on purpose. Intent is a big issue in a criminal matter. So, if the banana peel landed there totally by accident, you slip on it, and ultimately sue, you will be awarded monetary damages if you win. If the mad banana peel serial placer is doing it, he or she could be charged criminally for intentionally placing it there.
So, for the purpose of a crime scene, evidence is described as “something that can be legally submitted to a court of law as a means of determining the truth of the alleged matter of fact under investigation before the court.”
Let’s read over that definition carefully. “Something that can be legally submitted” is VERY important. If evidence is not collected or submitted legally, it cannot be used in court. If it is, and that evidence is the only thing holding the criminal case together, a good defense attorney will move the court to have the evidence thrown out (legally, not figuratively), and thus, the case can be dismissed.
Here’s an example of what I mean. In New Jersey, the New Jersey Supreme Court has ruled that if a person throws out garbage, and places it in a can or bag by the curb for pickup by a garbage company, it is still considered the person’s property until it is actually picked up. So, if the police suspect a person of producing counterfeit money, and they feel he may be throwing the work product away, such as too much ink used, paper ripped, etc., they can take his garbage bags BUT they cannot look in them for the evidence UNLESS they get a search warrant first. A search warrant is a legal authorization by a judge. So, if an officer takes the bags, opens them up without a search warrant, finds some counterfeit money, then arrests the suspect, he has seized evidence illegally. That means if the suspect appeals the evidence seizure, and the judge rules that it was seized illegally, the case will be dismissed and the suspect not charged. This is what is known as the “Fruit of the Poisonous Tree” doctrine. In other words, if the tree (the evidence) is poisonous, so will all the fruit borne by it (the criminal charges).
The example I just gave you about the garbage is the way New Jersey laws read – keep in mind each state has different laws. The only laws that apply to all fifty states is federal law, which is not the type of law that would cover the scenario about the garbage bags.
In your writing, you may want to actually have the police slip up and take evidence illegally. Of course, by slip up, your character could do so innocently by error . . . or do so on purpose and hope no one catches on. That was kind of Dirty Harry’s M.O. “The ends justify the means” growled Clint Eastwood. That may make for some interesting legal wrangling later in the book. Maybe the sharp defense attorney will catch it – maybe not.
“How big should my evidence be?” writers have asked me as well.
Evidence can be as small as a hair, or as large as an airplane, or anything in-between.
As examples, a hair found on a deceased’s shirt who has been murdered may be traced to his lover . . . or boss . . . or neighbor. Evidence this small is classified as “trace evidence” because of its small size.
In the case of the World Trade Center terrorist attack, the evidence was as large as the airplanes that hit the towers. Of course, there was much more evidence as a result of that attack, but the largest evidence was the airplanes.
Now that we have the legal mumbo-jumbo out of the way, in my next post on this subject, we’ll cover the different actual types of evidence (physical or real versus testimonial), as well as the purpose of these types of evidence, the important differences between them, and the two different classifications of evidence; evidence with individual characteristics versus evidence with class characteristics. Not to worry . . . I will have many different examples to help you in your great novel.