Some of our readers may have been surprised or taken aback at our last post, in which a judge prevented the prosecution from introducing some testimony at a defendant’s trial. It was determined that the testimony would have had a prejudicial effect on the jury.
In some ways, this may seem contradictory. Aren’t both sides of a criminal trial trying to sway the jury to their point of view? Isn’t their job to convince the jury that they are telling the truth? Why would a judge allow some evidence or testimony to be used, but not others? The answer is that there are rules for what kind of evidence is considered “admissible” and what is not. Generally speaking, evidence must be relevant, material and competent.
When we say that evidence must be relevant, that means that it tends to help either prove or disprove a fact. It doesn’t actually have to do either, just help make an argument in some way. Ultimately, the judge or the jury will decide how important that evidence is, whether or not to accept the fact at hand. But either side of the case can use evidence, as long as it’s considered relevant, to try to influence thinking in that regard.
Evidence must also be “material,” meaning it is used to prove a disputed fact in the case. If evidence is trying to prove something that’s not involved in the case — perhaps that someone committed a crime for which they are not currently being charged — it may be barred as immaterial. Finally, when we say that evidence must be “competent,” we are simply saying that is comports with what people generally think of as reliable. Evidence without a credible source, for example, or allegations of completely implausible actions may be considered incompetent.
In reality, many of us have details of our lives that could be made to appear incriminating if taken out of context and held up in court for scrutiny. But this idea that there should be rules regarding what kind of evidence should be admissible in court can help protect defendants from overzealous prosecutors in certain situations.