Our guest blogger is Chris Geidner, an attorney who blogs at Law Dork, 2.0. You also can follow him at chrisgeidner on Twitter.

Concerns about marketplace failures require Congress to enact real changes altering the marketplace to ensure economic stability. Unfortunately, recent Supreme Court rulings raise questions about how far Congress can go in its regulatory mission.

The Court confronted challenges like these at the turn of the last century, and it likely will do so again as Congress and the President mobilize plans to reinvigorate the regulatory framework of our national government, implement health care reform and combat the effects of global warming.

How much power Congress has under the Commerce Clause is one of the areas in which a Justice Sonia Sotomayor — by her vote or, more importantly, through her leadership — could alter the workings of the Supreme Court. But it’s an area in which we don’t have much insight into her thoughts on the matter.

In 1936, the Supreme Court struck down wage and working condition requirements and hours limitations of a mining regulatory law in Carter v. Carter Coal Co. as falling beyond the scope of Congress’s authority, holding that “production is not commerce; but a step in preparation for commerce.” Although the Court soon turned away from such a theory of the Commerce Clause, the cramped reading, far from gone, recently has been revived.

In 1995, the Court struck down a provision of the Gun-Free School Zones Act in United States v. Lopez as violating Congress’ authority under the Commerce Clause. Soon thereafter, portions of the Violence Against Women Act were struck down in United States v. Morrison under the same theory.

The strongest dissent in both of these cases was authored by Justice Souter, the mild-mannered jurist who has been the Court’s chief proponent of the value of stare decisis. In Morrison, he arguably refused to concede to the precedential value of the Lopez opinion, stating, “Why is the majority tempted to reject the lesson so painfully learned in 1937?”

It was a question that needed asking. This line of cases hasn’t been greatly expanded in recent years. But then, nobody should expect it would’ve been. Republicans controlled both other branches of government during much of the time since, and regulatory laws were generally diminished, not expanded. Today, though, as President Obama and congressional Democrats seeking to expand the regulatory role of government, Souter’s voice might be needed once again.

With Souter’s retirement, then, the question we’re left to consider is two-fold: (1) Would a Justice Sotomayor come down on the same side of the issue as Souter, and, if so, (2) would Sotomayor carry on Souter’s legacy of vigorously fighting for congressional power in the Commerce Clause area?

Unfortunately, we don’t have much to go on from Judge Sotomayor’s rulings from the bench. Of the five cases in which Judge Sotomayor has participated where challenges were brought to various statutes following Lopez, none shed any real light on her view of the Commerce Clause because there are so few. More, those that exist do not present any significant issue in which her interpretation of the Commerce Clause, when freed from the constraints of the Circuit Court, could be gleaned.

One could presume from a generalized look at some of Sotomayor’s other opinions, from civil rights cases to class action lawsuits, that she is likely to vote the same way as Souter on such challenges to congressional power.

Justice Souter, however, left an admonition in Morrison — that “today’s ebb of the commerce power rests on error, and . . . leads me to doubt that the majority’s view will prove to be enduring law” — that calls for more. Progressives should be looking in Sotomayor for a leader who can turn Souter’s doubt into reality.