Answer:
understand the charges and can work with his or her lawyers
Step-by-step 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.