A more thorough explanation:

The death-knell doctrine is a rule that allows an interlocutory appeal if waiting until final judgment would make the issue on appeal irrelevant and harm the appellant's rights. It is an exception to the final-judgment rule. For example, if a temporary restraining order is denied, the lack of an appeal would leave nothing to be considered in the trial court, so the death-knell doctrine allows an immediate appeal. However, the U.S. Supreme Court limited the doctrine in Coopers & Lybrand v. Livesay, stating that it does not permit an immediate appeal of an order denying class certification.

• If a company is denied a temporary restraining order to stop a competitor from using their patented technology, the death-knell doctrine would allow an immediate appeal to prevent irreparable harm to the company's rights.
• However, if a court denies class certification for a lawsuit against a company, the death-knell doctrine does not apply, and the company must wait until final judgment to appeal.

These examples illustrate how the death-knell doctrine allows for immediate appeals in certain situations to prevent irreparable harm to the appellant's rights.