The Massachusetts Constitution is the oldest active constitution in the world — it has been in effect for 228 years. While the state has amended the original document many times since its passage, its essential provisions, which have remained largely unaltered, are undoubtedly the work of a single man — John Adams. John Adams, routinely neglected among scholars, is essential to the development of American political thought. The purpose of this study is to put a magnifying glass on two important aspects of John Adams's life and give them the detailed study that they deserve: his legal career and its impact on the Massachusetts Constitution. The link between his legal career and his political theory is crucial to understanding that document. To write about John Adams's political thought without understanding the two-decade long legal career that drove so much of it leaves one with only a shallow understanding of how that thought developed. It was through the study of numerous legal authors along with his reflection and experiences as an attorney that Adams came to understand how vital the law was for a nation. Indeed, for Adams, law was the basis for good government itself, "to the end that it may be a government of laws and not of men."