Final answer:
Roosevelt's argument for the expansion of the Bill of Rights to include economic wellness falls under the principle of Substantive Due Process, which is part of the Fifth and Fourteenth Amendments and addresses fair and impartial treatment by the government, including economic rights.
Step-by-step explanation:
The constitutional principle that frames Roosevelt's argument for the expansion of the Bill of Rights to address the economic wellness of citizens is Substantive Due Process. Substantive due process is a component of the due process clauses found in both the Fifth and Fourteenth Amendments of the United States Constitution. These clauses protect citizens from the arbitrary denial of life, liberty, or property by ensuring not only procedural justice but also that all individuals must be treated fairly and impartially by government officials. This concept extends to government actions that could affect the economic rights and liberty of individuals, highlighting the intimate relationship between economic rights and overall individual liberty in the United States.