In this essay I want to argue that, if the aim of legal theory is to investigate the concept or nature of law, then it should utilize philosophical analysis to achieve its objective by showing how legal theory is linked to social theory. Due to the complicated nature of this mission, in this study I will explore this question from one particular theoretical viewpoint, namely speech act theory, particularly the theory of the illocutionary act developed by John Searle. In the second part the main elements of speech act theory will be explained briefly, including those concepts such as illocutionary act, illocutionary force etc. Next, I will analyze some legal theoretical positions by applying speech act theory, and then in the fourth part I will argue that we should instead attain legal validity by applying legal validation or validating a norm as legal. The chief element for this substitution is the illocutionary act. In the fifth part I will try to show that constructive interpretation is a novel kind of illocutionary act. We often see how, through the process of emancipations and struggles, certain kinds of legal status have been established by performing illocutionary acts leading to constructive interpretation. The social theoretical implications of this theory are shown thus by such outcomes. In the sixth part I then discuss this implication further. The main idea is to point out that social structure is also a kind of capability to enable more and more people to perform illocutionary acts and have their new status recognized through this process.