No one can do an impossible act or be required to do an impossible act. Recognising this, the courts developed the common law principle that a contract which has become impossible to performance can be terminated on the grounds of frustration by either party. The force majeure clause or the impossibility clause either expands the scope of the impossibility principle or attempts to limit its application by allowing time for the impossibility to subside. Significantly, the question has arisen if the changes in the market conditions or financial impossibilities can be the ground for frustrating a contract. The chapter details the impossibility principle and explores the force majeure clauses.