When people are facing Colorado criminal charges, the prosecution may rely on many different pieces of evidence to try to prove their case. However, some of that evidence may not be as strong as it appears. This can include allegations that a person is lying.
Lie detector tests
There are several different methods that law enforcement may use to try and detect lies. One is a polygraph test. In Colorado, the results of these tests cannot be presented in a criminal trial. Studies have shown that lie detector tests are not reliable. They are based on the idea that a person who is lying has certain physical reactions, such as a change in their pulse or blood pressure. However, other factors, including the stress of the test itself, could cause those same changes.
Physical and verbal cues
There is also a belief that body language can convey that a person is lying, but this is also unsupported by research. Furthermore, verbal cues are not reliable in determining whether an individual is lying. While studies have found that more complex statements might be true while lies may be simpler, there has not yet been enough research in this area. Even inconsistencies as people are questioned about their statements do not necessarily indicate lying. Understanding this can be helpful when defending against criminal charges.
Beyond the polygraph, there have been efforts to use technology to better detect lies, including MRIs and artificial intelligence. There still is not evidence that these are accurate enough, particularly in real-world settings.
Law enforcement may begin building a case based on an instinct that a person is lying. However, while it might someday be possible to detect lies with a high degree of accuracy, this is not yet true for existing techniques and technology.