I think you think there's some line buried in the constitution about protecting the free market.
Yeah, Basically. At least for government to stay out of it.
The truth is that the Constitution grants Congress 17 specific (or "delegated") powers. And it commands in the Ninth and 10th Amendments that the powers not articulated and thus not delegated by the Constitution to Congress be reserved to the states and the people.
What's more, Congress can only use its delegated powers to legislate for the general welfare, meaning it cannot spend tax dollars on individuals or selected entities, but only for all of us. That is, it must spend in such a manner -- a post office, a military installation, a courthouse, for example -- that directly enhances everyone's welfare within the 17 delegated areas of congressional authority.
And Congress cannot deny the equal protection of the laws. Thus, it must treat similarly situated persons or entities in a similar manner. It cannot write laws that favor its political friends and burden its political enemies.
There is no power in the Constitution for the federal government to enter the marketplace since, when it does, it will favor itself over its competition. The Contracts Clause (the states cannot interfere with private contracts, like mortgages), the Takings Clause (no government can take away property, like real estate or shares of stock, without paying a fair market value for it and putting it to a public use), and the Due Process Clause (no government can take away a right or obligation, like collecting or paying a debt, or enforcing a contract, without a fair trial) together mandate a free market, regulated only to keep it fair and competitive.
It is clear that the Framers wrote a Constitution as a result of which contracts would be enforced, risk would be real, choices would be free and have consequences, and private property would be sacrosanct.
The $700 billion bailout of large banks that Congress recently enacted runs afoul of virtually all these constitutional principles. It directly benefits a few, not everyone. We already know that the favored banks that received cash from taxpayers have used it to retire their own debt. It is private welfare. It violates the principle of equal protection: Why help Bank of America and not Lehman Brothers? It permits federal ownership of assets or debt that puts the government at odds with others in the free market. It permits the government to tilt the playing field to favor its patrons (like J.P. Morgan Chase, in which it has invested taxpayer dollars) and to disfavor those who compete with its patrons (like the perfectly lawful hedge funds which will not have the taxpayers relieve their debts).