Consesus Basoeta which is a cooperation agreement between the Government through the Ministry of Transportation of the Republic of Indonesia to the state owned enterprises PT. Kereta Api Indonesia (Persero), the agreement requires PT. Kereta Api Indonesia to perform the construction of public facilities and railways Soekarno Hatta Airport through the city of Tangerang, it is known that the cooperation agreement is an assignment form of the President of Indonesia Decree Number 83 of 2011. As the general agreement, then the Basoetta conappropriation should adopt the principles that become the fundamental conditions in the establishment of a treaty. Therefore, in this research, the author was asking whether the cooperation agreement between the Governments through the Ministry of Transportation of the Republic of Indonesia with PT. Kereta Api Indonesia is already reflecting the sense of fairness for the parties. Through this research, it is known that the Basoetta conappropriations have not fulfilled the element of justice, because the principle of conapproprialism implies that the treaty occurs because of the agreement or the free will of the parties who make the agreement on the contents or subject of the agreement. However, according to the Presidential Decree Number 83 of 2011 on the assignment by the president to PT.Kereta Api Indonesia for organizing the facility and facilities of railway Soekarno-Hatta Airport and the Jakarta-Bogor-Depok-Tangerang-Bekasi round about, PT. Kereta Api Indonesia shall accept the assignment and relieve the right to reject the assignment in the form of the agreement.