Conventional wisdom predicts a smooth confirmation process for Judge Sonia Sotomayor. Many say her appointment as Justice David H. Souter’s replacement would simply maintain the balance of the court, and many pundits emphasize that President Obama is simply trading one “liberal” for another.

This reasoning is flawed in minimizing the serious nature of any Supreme Court nomination — undervaluing the significance of a lifetime appointment to a court that bears the responsibility of defending the Constitution. Any nominee warrants an inquiry into his or her views on the Constitution and willingness to respect the judiciary’s limited role in our democracy.

The outcome of activist judges’ unwillingness to respect the limited role of the judiciary is well known as it relates to social issues. Justice Souter himself was quite expansive when it came to the authority of the court to rule on cases concerned with protecting the rights of the unborn and the role of religion in the public square.

This narrow focus on Justice Souter’s rulings on social issues has led to the claim that Mr. Obama is merely trading one liberal for another.

But there were other areas, such as those affecting free enterprise, where Justice Souter’s decisions were much more constrained and deferential to government’s two other branches, specifically relating to determinations that markets needed to be protected from overreaching liability, litigation risk or federal regulation. This was the case in areas such as shareholder liability, punitive damages, labor issues, class actions, antitrust and tort liability cases.

As the Senate determines whether Judge Sotomayor is qualified to serve on our nation’s highest court, I believe it is imperative that we carefully review her record.

Activist judges present a threat not only to our social policy, but also to our economic stability.

We have heard much about a 1996 article written by Judge Sotomayor in which she approvingly discussed the view of some legal scholars that the “indefiniteness” of the law is something to be celebrated. Any small-business owner knows, however, that job creation, investments in emerging technology or the expansion of stores or factories will not happen in a judicial climate where law is not knowable, consistent and predictable. People do not make investments and take the risks associated with expanding a business if they have no assurances that the law will protect them.

I look forward to learning how Judge Sotomayor addresses these realities in her judicial philosophy.

Every Supreme Court nomination is a reminder that the Constitution is a fragile but vital document — vulnerable to justices whose goal may be to create policy from the bench.

This is especially important to bear in mind today, when some of our government leaders have invoked economic crisis to justify abandoning a number of constitutional and legal limits on the national government’s power. The bailout program’s ever-changing responsibilities and authorities to wield taxpayer money without many checks and balances is just one example.

Hopefully, the confirmation process will be an opportunity to refresh our memories about the importance of our system of checks and balances on our three branches of government, which includes constitutional limits on our judicial branch.

It should instill a greater zeal to have our other branches defend that system when enacting future laws and programs.

Sen. David VITTER is a Louisiana Republican.