Aperson who is accused of a crime cannot be convicted if he or she is mentally unstable either at the time of the crime or at the time of the trial. this minimum standard of competence to stand trial is important to ensure that the person:

understand the charges and can work with his or her lawyers

Explanation:

The purpose of this rule is to give the defendants the chance to defend themselves from accusations in their best possible form.

Under mentally unstable situation, most people wouldn't:

-  be aware of their actions since their decision making process was heavily impaired

- Wouldn't be able to fully recollect information from the past.

Both of these things would make it extremely hard for the defendant to provide enough information for the lawyers and create a defense for the accusation.

can you give more details

well considering i can't see the graph, it's probably prices