Forensic evidence

Civil law

Circumstantial evidence is used in civil courts to establish or deny liability. It is usually the most common form of evidence, for example in product liability cases and road traffic accidents. Forensic analysis of skid marks can frequently allow a reconstruction of the accident. By measuring the length of such marks and using dynamic analysis of the car and road conditions at the time of the accident, it may be found that a driver underestimated his or her speed. Forensic science and forensic engineering are common as much in civil cases as in criminal.

Criminal Law

Circumstantial evidence is used in criminal courts to establish guilt or innocence through reasoning.

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 mens rea levels of "purposely" or "knowingly." The same goes for tortfeasors in tort law, if one needs to prove a high level of mens rea to obtain punitive damages.

One example of circumstantial evidence is the behavior of a person around the time of an alleged offense. If someone was charged with theft of money and was then seen in a shopping spree purchasing expensive items, the shopping spree might be circumstantial evidence of the individual's guilt.

Forensic evidence

Other examples of circumstantial evidence are fingerprint, blood analysis or DNA analysis of the evidence found at the scene of a crime. 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 to be circumstantial in nature. However, when proved by expert witnesses, they are usually sufficient to decide a case especially in the absence of any direct evidence. Owing to the development in forensic methods, old undecided cases (or cold cases) are frequently resolved.

A popular misconception is that circumstantial evidence is less valid or less important than direct evidence. This is only partly true: direct evidence is popularly, but mistakenly, considered more powerful. In fact many successful criminal prosecutions often rely largely or entirely on circumstantial evidence, and civil charges are frequently based on circumstantial or indirect evidence. Much of the evidence against convicted American bomber Timothy McVeigh was circumstantial, for example. Speaking about McVeigh's trial, University of Michigan law professor Robert Precht said, "Circumstantial evidence can be, and often is much more powerful than direct evidence". The 2005 murder trial of Scott Peterson trial was another high-profile conviction based heavily on circumstantial evidence.