A more thorough explanation:

The captive-audience doctrine is a principle in constitutional and labor law that restricts speech when the listener cannot practically escape from intrusive speech.

Under the captive-audience doctrine in constitutional law, speech can be restricted when the listener is unable to escape from it. For example, if a person is in a public place and someone is shouting at them, they cannot easily leave the area to avoid the speech. In this case, the speech can be restricted to protect the listener's rights.

In labor law, the captive-audience doctrine is also known as the captive-audience rule. It prohibits either party to a union election from making a speech on company time to a mass assembly of employees within 24 hours of an election. This is to prevent employers from using their power to influence the outcome of the election by forcing employees to listen to their views.

For example, if an employer holds a mandatory meeting for all employees to discuss the upcoming union election, this could be considered a violation of the captive-audience rule. The employees are a captive audience because they are required to attend the meeting and cannot easily leave to avoid the speech.