In the 1819 Supreme Court case McCulloch v Maryland, Chief Justice John Marshall wrote that “[the Constitution’s] nature ...requires that only its great outlines should be marked, its important objects designated, and the minor ingredients which compose those objects be deduced from the nature of the objects themselves...We must never forget that it is a Constitution we are expounding.” This process of deducing and expounding has been guided by a set of supplementary texts, practices, and principles which have become part of an unwritten Constitution. But how does something become part of this tradition? To answer this question we must not only look at the existing components of the unwritten Constitution, we also have to understand the historical context in which they emerged.
A primary component of this tradition is the Declaration of Independence. Its themes of self-governance, equality, and individual liberty guide us in interpreting the terse text of the 1787 document. Looking at the Constitution in the context of the Declaration, we can better understand and interpret key parts of the Bill of Rights. For instance, the Third Amendment's protection against the quartering of soldiers in private homes is directly related to a grievance in the Declaration. Also, interpreting the Ninth Amendment’s vague language of “rights retained by the people” is more easily understood in this broader context. So, the Declaration of Independence provides the philosophical and historical foundations for interpreting the written Constitution.
With the philosophical foundations put in place, we can then turn to the process of ordainment and ratification as a second tool for expounding the written text. This process included a national discussion which saw the document come to life in debates across the states. The Constitution itself was printed in papers for all to read and discuss, but so were letters both in favor of and against ratification. This experience strengthened the bonds of a participatory democracy and showed the importance of both free speech and a free press.
While the bonds of democracy were strengthened during the nationwide debate, the democratic legitimacy of the Constitution was strengthened by the inclusiveness of its ratification process. When it was time for the people to select their convention delegates, states lowered or completely dropped property qualifications for voting - a radical concept for the time.
Both of these ideas - open debate and more inclusive voting - give us a context for better understanding the birth of the Constitution. They also start a tradition that is more fully realized over time under the lived Constitution.
Subsequent generations have added their voice to the unwritten Constitution through a set of emerging practices, or what Professor Akhil Reed Amar calls “hearing the people.” For instance, certain legal practices that are currently taken for granted were not common during the founding generation. Concepts such as testifying in court on one’s own behalf, proof beyond a reasonable doubt, and providing evidence for one’s defense have emerged over the past two centuries. This “lived Constitution” as Amar calls it, has given those generations that have followed the founders, the ability to mold the legal and political culture under which they have lived.
So, for something to be part of America’s unwritten Constitution, it must be part of an emerging and evolving legal, political, and cultural landscape. In short, it means being part of the process of expounding the written Constitution.