A second appeals court has ruled on health-care reform’s “individual mandate.” It is now more likely that this issue will be decided at the Supreme Court. When the court considers the case, three intersecting legal doctrines will play a role: Congress’ power over interstate commerce; the “necessary and proper” clause; and the “police power.”

By the middle of the 20th century, after cases had expanded, contracted and again expanded what the Constitution allowed, it was generally held that that power to “regulate commerce among the several states” included activities that occurred only within one state when they affected interstate commerce. The Supreme Court drew a line keeping this power from being read too broadly in the Lopez (1985) and Morrison (2000) cases where federal laws on gun possession near schools and gender-related violence were overturned. Alleged connections to the national economy were not enough. Activities not “in” or “of” the economy seemed beyond Congress’ power.

But a more recent — 2005 — case undermined this economic/noneconomic distinction. The court held that federal law forbidding the cultivation of marijuana trumped state laws that permitted personal growth of marijuana for medical purposes. Congress could regulate “purely local,” noncommercial activities that had a “substantial economic effect on interstate commerce.” The court agreed with the government there was a rational basis to conclude that legal cultivation of small amounts of marijuana affected the interstate market in illegal marijuana.

In this decision, the court accepted the claim that forbidding medical marijuana was essential to combating the illegal drug market. The congressional findings on the individual mandate state that it is “essential” to the law. Does that make it constitutional? It may, if we consider another clause in the Constitution: Congress has the power “to make all those laws necessary and proper” for achieving granted powers.

From the time of its 1819 decision upholding the national bank, the Supreme Court used an ends-means test to determine if Congress may exercise powers not specifically granted in the Constitution. If the purpose of the law is legitimate and constitutional, all means that are “appropriate” and “not prohibited” are constitutional. But necessary-and-proper reasoning doesn’t end the individual mandate debate.

Decisions on this issue also consider a legal principle, not actually in the Constitution: the “police power”—the ability of government to provide for the health, safety and morality of its citizenry.

U.S. constitutional law has held for a long time that the states possess this police power but that there is no federal police power. Thus, those who support the Massachusetts plan enacted under then-governor Mitt Romney can logically oppose the federal mandate.

But it is also possible to argue that the police power of the states and federal authority under the “necessary and proper” clause can exist concurrently. In the 2010 Comstock case, the Supreme Court — with only Justices Clarence Thomas and Vincent Scalia dissenting — upheld the civil commitment of federal inmates who were determined to be mentally ill and sexually dangerous at the end of their sentences. Against a claim that the commitment process was part of the police power, the court ruled that the federal government, as legal custodian of these prisoners, had the responsibility not to release them. Control of the conditions of release was an activity that was necessary and proper to the government’s effective power to enact laws and punish their violation.

Where, then, are the constitutional lines going to be drawn around the individual mandate? While attorneys for the different sides will, of course, take the position that the law is settled — in their favor — the threads of explicit and implied constitutional powers suggest that the outcome is far from clear. Most likely, whatever the Supreme Court’s decision, the issue will play a role in the elections of 2012.

Susan Grogan, Hollywood

The writer teaches political science at St. Mary’s College of Maryland. Her full discussion of these issues is available at http://ssrn.com/abstract=1912532.