Effective mediation requires that the parties and the mediator be able to invoke a privilege not to testify about communications made in the course of mediation. Federal Rule of Evidence 408 and similar provisions in approximately half of the States serve mediation confidentiality by prohibiting the admissibility of offers of compromise 'to prove liability for or invalidity of the claim or its amount.' Also, many mediation programs use contracts between mediating parties to guarantee confidentiality. Some programs have reached informal agreements with courts and prosecutors to protect mediation confidentiality. A number of States have sought to protect mediation confidentiality in legislation. Such legislation should protect all mediation communications, with some exceptions. Unprotected communications should be those necessary to a suit pertaining to the mediation agreement or necessary to prove the breach of one party's obligations to another, such as a duty to bargain in good faith. Legislation should also prevent mediator testimony, except with both parties' consent and only then when such testimony would not impair the mediator's future effectiveness in mediation. A total of 117 notes are listed.