This Comment argues that § 10(b) of the Securities Exchange Act of 1934 and its implementing regulations are broader and more ambiguous than other administrative laws and regulations that carry criminal penalties. In fact, insider trading law is almost entirely judge-made, which is problematic considering the serious punishment criminal defendants face. Thus, this Comment advocates that in a criminal proceeding, Chevron deference should not apply to § 10(b) and its accompanying regulations. This Comment further argues that courts should apply the rule of lenity to resolve ambiguities in insider trading law in favor of defendants. In the alternative, this Comment suggests that if courts must apply Chevron deference, they should more readily challenge the rulemaking authority of the SEC at step two of the Chevron framework.