Circumstantial evidence is indirect evidence. Circumstantial evidence is the result of combining seemingly unrelated facts that, when considered together, can be used to infer a conclusion. Circumstantial evidence is usually a theory, supported by a significant quantity of corroborating evidence.
Circumstantial evidence is used in criminal courts to establish guilt or innocence through reasoning.
The distinction between direct and circumstantial evidence is important because, with the obvious exceptions (the immature, incompetent, or mentally ill), nearly all criminals are careful to not generate direct evidence, and try to avoid demonstrating criminal intent. Therefore, to prove the mens rea levels of "purposely" or "knowingly," the prosecution must usually resort to circumstantial evidence. The same goes for tortfeasors in tort law, if one needs to prove a high level of mens rea to obtain punitive damages.
An example of circumstantial evidence is the behavior of a person around the time of an alleged offense. If someone were charged with theft of money, and were then seen in a shopping spree purchasing expensive items, the shopping spree might be regarded as circumstantial evidence of the individual's guilt.
A popular misconception is that circumstantial evidence is less valid or less important than direct evidence. This is only partly true: direct evidence is generally considered more powerful, but successful criminal prosecutions often rely largely on circumstantial evidence, and civil charges are frequently based on circumstantial or indirect evidence. In practice, circumstantial evidence often has an advantage over direct evidence in that it is more difficult to suppress or fabricate.
Much of the evidence against 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 recent Scott Peterson trial was based heavily on circumstantial evidence.
Circumstantial evidence is also used in civil courts to establish or deny liability.
However, there is sometimes more than one logical conclusion inferable from the same set of circumstances. In cases where one conclusion implies a defendant's guilt and another his/her innocence, the 'benefit of the doubt' principle would apply.