SEC enforces many rules... I can't think of a "best" example.
Recently, SEC implemented a rule to force corporate executives to disclose, in plain English, their salaries and benefits. In the past, CEOs of companies that lost miillions of dollars every year received enviable compensations despite their poor performance, and they did so without public knowledge. No more of that, unless they want to spend some quality time behind bars.

Ooh, quality time! That's a nice bonding experience with your fellow man.
Don't think of messing with them Master Chan... you must have some scheme brewing somewhere... j/k :P