1. (1) A contract to make a will or devise, or not to revoke a will or devise, or to die intestate, executed after January 1, 1974, shall be established only by:

   1. (a) Provisions of a will stating material provisions of the contract;
   2. (b) An express reference in a will to a contract and extrinsic evidence proving the terms of the contract; or
   3. (c) A writing signed by the decedent evidencing the contract.
2. (2) The execution of a joint will or mutual wills does not create a presumption of a contract not to revoke the will or wills.

[1973 c.506 §13]