Final answer:
Being charged with a serious crime and receiving a subpoena to testify require a mandatory court appearance.
Step-by-step explanation:
The two factors that require a mandatory court appearance are:
- Being charged with a serious crime
- Receiving a subpoena to testify
When someone is charged with a serious crime, they are required to appear in court to face the charges brought against them. Additionally, when a person receives a subpoena to testify, they are legally obligated to appear in court and provide their testimony under oath.