Reasonable doubt is described as the highest standard of proof used in court and means that a juror can find the defendant guilty of the crime to a moral certainty.
Even when circumstantial evidence is not sufficient to convict or acquit, it can contribute to other decisions made about the case.
For example, a forensic scientist or forensic engineer may provide results of tests indicating that bullets were fired from a defendant's gun, or that a car was traveling over the speed limit, but not necessarily that the defendant fired the gun or was driving the car.
It is usually the most common form of evidence, for example in product liability cases and road traffic accidents.
By measuring the length of such marks and using dynamic analysis[clarification needed] of the car and road conditions at the time of the accident, it may be found that a driver underestimated his or her speed.
With obvious exceptions (immature, incompetent, or mentally ill individuals), most criminals try to avoid generating direct evidence.
Hence, the prosecution usually must resort to circumstantial evidence to prove the existence of mens rea, or intent.
These types of evidence may strongly point to a certain conclusion when taken into consideration with other facts—but if not directly witnessed by someone when the crime was committed, they are still considered circumstantial.
In cases where one conclusion implies a defendant's guilt and another his innocence, the "benefit of the doubt" principle would apply.
Speaking about McVeigh's trial, Robert Precht said, "the prosecution's use of indirect evidence is no cause for worry".
Another case that relied on circumstantial evidence was that of Nelson Serrano, who received four death sentences for four first-degree murders.
[13] In Singapore, law student Sunny Ang was sentenced to death in 1965 solely based on circumstantial evidence when he was convicted of murdering his girlfriend during a scuba diving trip near Sisters' Islands on 27 August 1963.