Here is an interesting paper that argues that SOX actually encourages worse corporate governance.
We argue that obligatory compliance with stricter financial reporting rules (e.g., the US Sarbanes-Oxley Act) may entail important unintended consequences. Paradoxically, the amount of misreporting may increase because corporate boards spend more valuable resources fulfilling statutory mandates rather than involving themselves in forward-looking strategy setting. As these surveillance devices are substitute methods of gauging management quality, when boards focus on the firm's internal control and accounting system they become semi-detached from strategy – their business acumen falters. Top executives are then judged primarily on the basis of financial metrics as opposed to long-term fit. As the balance sheet review carries more weight in the board's decision-making process, the return to managerial book-cooking (a purely influence activity) and the risk of endorsing flawed business plans swell.
After reading the paper I didn't come away feeling convinced, yet at the same time, there seems to be a kernel of truth to this. If you are into this kind of thing, check it out and just skim the mathematics.