Tyson Arbuthnot
David E. Aron
Gayle M. Athanacio
Stephen L. Bacon
Merri A. Baldwin
Robert J. Breakstone
Dennis J. Callahan
Thomas H. Carlson
Jeffery M. Chiow
Alecia E. Cotton
Joshua M. Deitz
Robert C. Goodman
Lucas T. Hanback
John G. Heller
Dennis C. Huie
Suhani Kamdar
Lauren B. Kramer
S. Amber Lee
Mark J. Linderman
E. Jacob Lubarsky
James Robert Maxwell
Joseph C. McGowan
Patricia A. Meagher
Robert S. Metzger
Brian D. Miller
Alexis J. Morris
Nicholas T. Niiro
Roland Nikles
Neil H. O'Donnell
Dean D. Paik
Sharon Ongerth Rossi
Aaron M. Scolari
Aaron P. Silberman
Katherine M. Svinarich
Renée D. Wasserman
Alan J. Wilhelmy
Paul M. Zieff

Dennis J. Callahan
Download vCard

Areas of Practice

Mr. Callahan is a member of the firm’s Government Contracts, Complex Commercial Litigation and Construction Law Practice Groups.

Professional Qualifications

Mr. Callahan represents government contractors on a broad range of litigation matters, including false claims investigations and actions in the defense, construction, and medical industries; bid protests and contract claims at the federal, state and local levels; and prime/subcontractor disputes in state and federal court, arbitration and mediation. Mr. Callahan also counsels government contractors and grantees regarding their compliance with contract and legal requirements, accounting standards and audit practices.

Mr. Callahan has significant experience in the government contracts and construction industries. He has prosecuted and defended bid protests of contract awards involving major civil and facilities construction projects. He has investigated, prepared, and litigated requests for equitable adjustment, termination settlement proposals, and other claims involving billions of dollars of costs whose cause is disputed. In these matters, Mr. Callahan often works closely with forensic accounting firms, and he counsels client leadership on the timing, framing, and tone of the submissions and legal filings, and on negotiation and litigation strategy.

Mr. Callahan frequently contributes to bar publications and scholarly journals. Among other publications, his articles have appeared in the Procurement Lawyer, A.B.A. false claims acts and construction books, William & Mary Law Review, Cardozo Law Review, The Government Contractor, Legal Times (Washington), New York Law Journal, and The Federal Lawyer.


Hon. D. Brooks Smith, United States Court of Appeals for the Third Circuit,
2004-05 Term

Hon. Jackson L. Kiser, United States District Court for the Western District of Virginia, 2003-04 Term


J.D., William & Mary Law School

M.B.A., William & Mary Graduate School of Business

B.A., University of New Hampshire

Bar Admissions
District of Columbia
New York

Complex Commercial Litigation
Government Contracts

Recent Publications and Public Speaking

Procurement Fraud, Speaker, CLE International West Coast Qui Tam/False Claims Act Conference, Nov. 4, 2016

Sidestepping the Escobar Two-Step: United States ex rel. Rose v. Stephens Institute Rejects Two-Pronged Test, Bloomberg BNA, Federal Contracts Report, Oct. 18, 2016 (PDF)

Litigating Bid Protests Before the New York Office of State Comptroller, The Procurement Lawyer, June 2015 (PDF)

Bid Protests Before the New York Office of State Comptroller, State and Local Division of the ABA Public Contracts Law Section, Webinar, Mar. 27, 2015

State False Claims Acts: A Practitioner's Guide to the False Claims Acts of the Various States, ABA Publishing, 2014 (co-authored) ABA Webstore

2013 Government Contract Law Decision of the Federal Circuit, 63 American University Law Review 1307 (2014), (PDF) co-authored

Hoping for Summary Judgment on California False Claims? Au Contreras, AGC California Legal Brief, Mar. 2014, (PDF) co-authored

Government Shutdown Q & A: Navigating in Uncharted Waters, a CLE webinar for the Public Contracting Institute, October 15, 2013 (slide show)

If Budget Sequestration Trims Your Contract: What Contractors Need to Know About Partial Terminations and Deductive Changes (PDF) RJO Government Contracts Update, September 2012, co-authored

What Contractors Need to Know About Changes to State False Claims Acts, webinar for TechAmerica, September 11, 2012 (PDF) (co-presented) materials

Contractors Should Watch Out for Big Changes Coming to the California False Claims Act, California Constructor, by AGC California, September/ October 2012 (PDF) (co-authored)

Ninth Circuit Holds That False Estimates in Federal Bids Are Actionable Under the False Claims Act, RJO Government Contracts Update, August 2012 (PDF) (co-authored)

States Broadening Their False Claims Acts in Response to Federal Incentives, RJO Government Contracts Update, July 2012 (PDF) (co-authored)

"Preparing for Strengthened States False Claims Acts," ABA State & Local Procurement Division, June 22, 2012

A-12 Saga Continues
The Government Contractor, Vol. 52, No. 45, December 8, 2010
by N. O'Donnell and
D. Callahan


Robert Dollar Building
311 California Street, 10th Floor
San Francisco, CA 94104
Phone: 415.956.2828
Fax: 415.956.6457
Download vCard