Ratio decidendi is the reason for the decision of judge, as a legal reason and consideration that forms the basis of a judge's decision. The meaning of the perspective of the Pancasila Philosophy regarding the implementation of judicial power as the power of an independent state to administer justice in a general court environment in order to enforce law and justice based on Pancasila and the 1945’s State Constitution of the Republic of Indonesia. In judicial practice, the determination of the buyer in good faith with a land object is very dependent on the judge examining and trying the case in question. The construction of the judge's decision to buyers in good faith with a land objects includes two contextual components, a legal reasoning and a law making. Context of  legal reasoning is done by analogy, to concretize the principle of law in the provisions of a statutory regulation. Context of Law Making is based on the methods of interpretation.