A more thorough explanation:

Unauthorized practice of law refers to the act of practicing law without proper authorization or a license to do so. This can include providing legal advice, representing clients in court, or drafting legal documents without the necessary qualifications.

For example, if someone who is not a licensed attorney offers legal advice to a client, they are engaging in the unauthorized practice of law. Similarly, if someone who is not authorized to practice law represents a client in court, they are also engaging in this illegal activity.

Unavailability refers to the status or condition of not being available. This can occur when a witness is exempted by court order from testifying, or when someone is simply not able to be reached or contacted.

For example, if a witness is unable to testify in court due to a court order protecting them from having to do so, they are considered unavailable. This status can also be used as an exclusion to the hearsay rule in the Federal Rules of Evidence.