The title of the legal research is the unilateral termination of the agreement by the
provider of B3 and non-B3 waste in service agreements related to the management
and utilization of B3 and non-B3 waste which is determined to be an unlawful act
(Study of MA decision No. 1051 K/pdt/2014). The Supreme Court as an institution
that adjudicates at the cassation and review level issues a decision and serves as
jurisprudence, that unilateral termination of an agreement is an act against the law,
this is a big question on the juridical basis used by the Supreme Court. The purpose
of this legal research is to find out the juridical basis of the judges of the Supreme
Court regarding the unilateral termination of the agreement which is qualified as
an unlawful act, in the Supreme Court's decision. No. 1051 K/pdt/2014. This
research was conducted using normative methods, research that focuses on
statutory regulations, so that primary legal materials become the main legal
materials and secondary legal materials as supporting legal materials. The results
of the research are unilateral termination of the agreement is an act that violates
Article 1338 of the Civil Code, so in the case of PT. Chuhatsu Indonesia with PT.
Tenang Jaya Sejahtera is purely a unilateral termination of the agreement without
any errors in performance which causes the agreement to be void.