Michael Ronickher

Washington D.C. Office
T: 202.204.3503
F: 202.204.3501

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Michael Ronickher is Of Counsel in the Washington, DC, office of Constantine Cannon LLP. He represents a broad range of whistleblowers under a variety of federal and state programs, helping them bring to light fraudulent activities in industries as diverse as healthcare, technology, and defense. He also brings his experience at the Department of Justice to a particular specialty in representing financial or tax whistleblowers.

Prior to joining Constantine Cannon, Mr. Ronickher was a Trial Attorney in the Tax Division of the Department of Justice. In his almost nine years at the Department, he served as lead counsel on numerous complex and high-profile litigations. Mr. Ronickher has deep experience with the most complicated types of litigation, including in cases involving complex tax avoidance or reduction schemes. Mr. Ronickher has extensive experience picking apart complex tax shelters. For example, he helped develop the government’s defense against so-called “previously taxed income” (PTI) tax shelters that were being used to shelter the income from $870 million. Earlier in his career, he served on the trial team of the Wells Fargo case involving $115 million in deductions based on a series of 26 tax shelters known as SILO (Sale-In, Lease-Out) transactions.

Mr. Ronickher worked closely with the IRS whistleblower office when he represented the United States in John Doe v. United States, which concerned a tax whistleblower’s tip that potentially pointed to over $500 million in tax fraud, which could have yielded a whistleblower award of $75 million. Mr. Ronickher also defended a challenge to the IRS’s Report of Foreign Bank and Financial Accounts (FBAR) Offshore Voluntary Disclosure Program, which was the main route by which U.S. citizens with foreign bank accounts could disclose them in return for reduced consequences.

Mr. Ronickher developed and successfully litigated numerous other cases featuring complicated laws, regulations, and financial transactions, including a complex foreign tax treaty case and defending against a novel challenge to a Treasury Regulation that was hindering a land-flipping business. Mr. Ronickher also spear-headed the Tax Division’s litigation concerning the Section 1603 grant program, which provided a federal subsidy for clean-energy investments. He independently handled the first such case to go to trial and, more recently, he led the Government’s trial team in a $260 million case regarding the valuation of portions of the largest wind farm in the United States, which had been sold through a complex series of transactions.

While at the Department of Justice, Mr. Ronickher was awarded the Tax Division Outstanding Attorney Award on three separate occasions. He was the recipient of two awards from the IRS: the Mitchell Rogovin Award and the IRS Lucite Award. He has also served as a conference speaker on tax law issues. Mr. Ronickher graduated with distinction from Stanford Law School. While at Stanford, he was a Public Interest Fellow and co-editor of the Journal of Civil Rights and Civil Liberties. Mr. Ronickher completed his undergraduate studies at Dartmouth College, where he graduated summa cum laude with a degree in Comparative Literature. Prior to law school, he worked as an editor for the life sciences textbook publisher Benjamin Cummings. Mr. Ronickher is proficient in German.

Practice Groups


  • California
  • District of Columbia
  • U.S. Court of Federal Claims
  • U.S. District Court for the Northern District of California
  • U.S. District Court for the District of Colorado


2011 Panelist: "Litigation Involving Tax-Exempt Organizations"
D.C. Bar Association Conference

The London office of Constantine Cannon is a separate and independent limited liability partnership registered in England and Wales (with registered number OC376384) with a registered office at 1 Paternoster Square, London EC4M 7DX. Constantine Cannon LLP in London is authorised and regulated by the Solicitors Regulation Authority. The word "partner" denotes a member of Constantine Cannon LLP, or an employee or consultant with equivalent standing and qualifications. The professional rules applicable to the firm are available at the SRA website at www.sra.org.uk/rules.