In the bad old days, to get a securities licence, people had to sign a contract giving up their right to take employment disputes to the courts.

ECONOMIST: Wall Street

The Severance Payment : If an employee is already entitled to receive a severance payment, whether pursuant to an employment contract or company policy, there is no need to sign a severance agreement to get that money.

FORBES: The Top Ten Reasons to Hire a Lawyer to Review Your Severance Agreement

However, agencies are asking supply teachers to sign a contract - known as a Swedish Derogation - to waive this right in exchange for continuous employment or a minimum payment if work is not available.

BBC: Wales