If We Must Violate Libertarian Principles …

The current crisis has two parts:

• The creation of a large amount of bad debt.
• The spread of bad debt to the allegedly-sound parts of the financial system.

Preventing the next occurrence of the first is fairly simple. It's a matter of phasing out the politically-influenced GSEs that created the problem in the first place.

Preventing the second part is harder. The normal operation of the financial markets should confine problematic debt in a small part of the system where people who specialize in risky investments can deal with it. In other words, what were those financiers smoking?

It might make sense to take advantage of the de facto legalization of mind altering chemicals for anybody who isn't poor, to check which ones are correlated with the spread of bad debt and, if necessary, prohibit them, at least for people working in the financial sector.