Scientists accidentally kill world's oldest animal at age 507. The oldest animal ever known lived from 1499 until the day researchers cracked its shell open, killing it in the process.
For example, there is a federal law (and similar laws in every state) allowing consumers to cancel contracts made with a door-to-door salesperson within three days of signing. You might use that law after hastily agreeing to have someone repave your driveway, deliver lawn fertilizer, or put a new roof on your house.
There are some federal laws that allow parties to a contract to cancel or call off the contract within a few days of entering into them. These laws are often called cooling off rules and give the contracting parties the option of canceling a contract with a certain time period.