In every legal case the amount of evidence adequate for a person to win the case is called a burden of proof. There are different types of burdens of proof, depending on the type of case. In a typical civil case such as an auto accident, the burden of proof is a preponderance of the evidence. A preponderance means more likely than not. For example, if a person is suing a corporation for $1000.00 or $1,000,000.00 the burden is the same. The jury must ask based on the evidence presented is it more likely than not that the incident happened the way the plaintiff (person who files the civil action/lawsuit) claims. Another way to look at it is to assume there is an equally balanced scale. If the plaintiff tips the scale, even slightly, then under the law the plaintiff should prevail. There is no greater burden in these types of civil cases.
In some other cases like domestic cases where one party wants to prove adultery, or the State wants to permanently take child away from a parent, the side bringing the lawsuit must prove by clear and convincing evidence. Clear and convincing is a stronger level of evidence. The jury must be very sure of what the plaintiff has presented. This standard is obviously higher than a preponderance of the evidence.
The other legal burden is the strongest known in law. It is the burden that protects people from governmental power and authority. This burden represents the highest respect for freedom and liberty. This burden is the one used in criminal cases and it is beyond a reasonable doubt. In every single criminal case the prosecution must prove the person charged guilty beyond a reasonable doubt. In cases that are based on circumstantial evidence (no direct eye witness) the State must prove not only beyond a reasonable doubt but to the exclusion of every theory that is consistent with the person’s innocence. This means that if the evidence points toward guilt, but also points toward innocence, the jury must accept the theory of innocence. I remember reading the Sherlock Holmes mystery short stories and there was a great line I have never forgotten. It goes something like this: “Circumstantial evidence can point toward both guilt and innocence at the same time and with equal force, depending on the predisposition of the viewer.” Think about that for a moment. I hope you see now why the law requires doubts to be resolved in favor of the accused.