It’s been fifteen years since Congress codified the economic substance doctrine in section 7701(o), and we are still debating what it means and how it should apply, especially for corporate taxpayers.  This panel will examine how codification reshaped the doctrine’s analytical framework, increased penalty exposure, and raised the stakes for tax planning and structuring.  Panelists will trace how the IRS’s interpretation and application of the doctrine has changed over time and what the future might look like for enforcement, litigation, and administrative practice.  And they will discuss recent developments and what they mean for compliance, administrative predictability, and controversy.