Physical evidence can act as direct or circumstantial evidence

Evidence comes in many forms, such as eyewitnesses, participants, prior statements by the defendant, documents, physical evidence, and scientific evidence, like fingerprints or DNA. No matter the form, there are two basic kinds of evidence that may be admitted in court – direct evidence and circumstantial evidence.

Direct evidence does not require any reasoning or inference to arrive at the conclusion to be drawn from the evidence. Circumstantial evidence, also called indirect evidence, requires that an inference be made between the evidence and the conclusion to be drawn from it.

A common example used to illustrate the difference between direct and circumstantial evidence is the determination of whether it rained. On the one hand, if a person testified that he or she looked outside a window and saw rain falling, that is direct evidence that it rained. If, on the other hand, a witness testified that he or she heard distant pitter patter, and later walked outside and saw that the ground was wet, smelled freshness in the air and felt that the air was moist, those sensations would be circumstantial evidence that it had rained.

Circumstantial evidence is often discussed as if it carries less weight than direct evidence. Under the law - and in life - that is not necessarily true. The example above demonstrates that both direct and circumstantial evidence may be equally reliable. In both scenarios, there would be strong proof of rain. Any piece of evidence, whether direct or circumstantial, must be evaluated in terms of whether the source of the evidence is reliable.

An eyewitness to an event is direct evidence, but eyewitnesses are often unreliable for many reasons. People may lie, or, more often, they may not see things as clearly as they believe, especially if an event occurs quickly or at a time of high stress. Moreover, people tend to see things in a way that matches their expectations. Memory can change over time, and people tend to fill in gaps in their memory without realizing it. People are often susceptible to suggestion, whether by police or others.

While there are certainly differences between direct and circumstantial evidence, reliability is not necessarily one of them.