Treasury said the IRS has previously used the section to delay a penalty under the 2007 Small Business and Work Opportunity Act and a tax hike in the 2011 Airport and Airway Extension Act.
But both of those delays were for less than a year (six months and one month, respectively), only applied to minor portions of much broader legislation, and were issued the same year the original legislation passed.
By contrast, the Obamacare employer-mandate delay was issued more than three years after the original law passed, will be in effect at least a year (possibly longer), and involves a major cost saving feature of the underlying legislation.
Furthermore, there is simply no limiting principle to Obama’s chosen legal justification for the employer-mandate delay. If one year, why not two? If two years, why not four? If the employer mandate can be delayed, why not the individual mandate.
Nothing in 7805(a) in any way limits the president’s discretion, so, by using that as his sole legal justification, Obama is enabling himself and any future president to rewrite the law at will with no input from Congress.