In any personal injury case, it is the injured person's job to convince a judge or jury (or the insurance adjuster) that the person being sued is responsible for causing the injuries. This article discusses just how much convincing the plaintiff (the injured person) must do in a personal injury case, and how and when that burden of proof is applied.
All legal cases, whether civil or criminal, have certain evidence-related thresholds that must be met before a defendant can be found guilty or liable. The "burden of proof" refers to just how convinced the judge or jury must be before believing something.
People commonly understand this to mean how convinced the judge or jury is of the case as a whole, for example whether a criminal defendant is guilty of murder "beyond a reasonable doubt." However, the burden of proof applies to each individual element in a claim.
Personal injury cases are civil court matters, as opposed to criminal cases. The district attorney or other public official prosecuting a criminal case must prove each element of the case "beyond a reasonable doubt."
However, a plaintiff in a civil case -- including personal injury claims -- has a much lower burden of proof: the plaintiff must convince the jury that it is "more likely than not" that the facts are what he or she says they are. "More likely than not" (or "by a preponderance of evidence") essentially means the jury thinks the chance the plaintiff's version of the facts are true is at least 51%, while the chance they are false is no more than 49%. Fifty-fifty odds are not good enough.
The defendant is not required to prove her version of events is true. When the plaintiff is trying to prove the elements of the case, the defendant does not need to convince the jury of an alternative version -- all that is necessary for the case to fail is for the jury to believe that the chances are 50% (or more) that the plaintiff's version is inaccurate or false.
The defendant can of course present evidence of facts that contradict the plaintiff's version of events, but the jury does not need to be convinced that the defendant's version of the facts is the most accurate. The defendant's alternative facts simply act to cast enough doubt on the plaintiff's version that the jury no longer believes the plaintiff's version is "more likely than not" true.
An exception to this rule is when a defendant is trying to prove an "affirmative defense." An affirmative defense occurs when, regardless of the plaintiff's success in proving the elements of the claim, the defendant proves additional facts that defeat the plaintiff's claim. The defendant must prove the elements of an affirmative defense to be "more likely than not" true.
An example of an affirmative defense is assumption of the risk, which could arise in cases where the plaintiff was injured while participating in a sport. Even if the plaintiff successfully convinces the jury of all the elements of her case, if the defendant then successfully convinces the jury that plaintiff "more likely than not" agreed to participate in the sport, and the injuries arose in the normal course of the sport, the defendant will likely win the case.
The two essential elements of a civil battery claim are actual offensive or harmful contact with the plaintiff and the defendant's intention to cause that contact. The jury will be asked if it is more likely than not that "actual offensive or harmful contact" occurred, and if it is more likely than not the "defendant intended to cause the contact."
Let's say the plaintiff presents the testimony of a bartender who says she saw the defendant punch the plaintiff in face. The jury finds the bartender credible and finds it "more likely than not" that harmful contact occurred. When asked if it appeared that the defendant intended to punch the plaintiff in the face, the bartender says yes, that it did not at all appear to be an accident. Believing the bartender, the jury also finds it "more likely than not" that the defendant intended to cause the harmful contact.
If the defendant did not have an affirmative defense, the plaintiff would win the case at this point because he had met his burden of proof on all the elements of the battery claim. Imagine, however, that the defendant presents testimony from three different strangers who all testify that the plaintiff asked the defendant to punch him so that the plaintiff could show off his tough jaw. If the jury believes the testimony is more likely true than not, the defendant will meet his burden of proof for the affirmative defense of "consent" and win the case.