Mark's law practice occurs at the junction of all three branches of government. In the law-making process, he drafts legislation and ballot measures and also challenges initiative ballot titles and petitions; Campaigns & Elections Magazine has called him "Colorado's best election lawyer, bar none." In the courts, he litigates high profile policy and political matters, using trial strategies that the Denver Business Journal said "emphasize innovation over convention." And before executive branch regulatory agencies and licensing boards, he represents commercial clients including industry leaders in Colorado's limited gaming industry. For these reasons, Law Week Colorado named Mark the state's Best Government Lawyer in a Law Firm.