Wasn't Sarbox supposed to prevent this?

The effects of the subprime mortgage begs an obvious questions: wasn't Sarbanes Oxley supposed to prevent these sorts of things? The wrong-doing in the mortgage market is clear enough that people are right to ask this. One commentator in City Journal puts it this way: "But in the end, Sarbanes Oxley has just made it easier for ambitious government attorneys to criminalize bad business judgment and complex accounting in hindsight... the feds have passed up opportunities to create commonsense protections for investors." The article ends up advocating laws that would prevent most people from owning too much of one stock in their retirement accounts, an idea that makes some shudder. In the end, ambition, greed and the willingness to see no evil cannot be controlled by any law. Doesn't mean we don't need some laws, though costs are an issue. We just need to understand their limits.  

For more:
- here's the City Journal article
- here's an article