Derek E. Diaz serves as co-chair of Hahn Loeser’s appellate group. He brings a wealth of trial and appellate experience to complex commercial matters, including class actions and employee raiding cases. An Ohio State Bar Association Board certified specialist in appellate law, Derek’s clients include Fidelity National Financial Inc.; ExxonMobil Corp., Nucor Corp. and Century 21 Real Estate LLC.

Derek offers additional professional insights a one of the founders of the The Class-Action & Compliance Sentinel blog, which keeps real estate professionals apprised of new developments regarding class actions and compliance matters in that industry.  Derek also is a member of the firm’s Real Estate Industry Services group. He is a Life Member of the 6th Circuit Judicial Conference.


  • Ohio State Bar Association Board Certified Specialist in Appellate Law.
  • Partner, Hahn Loeser & Parks LLP, 2009 to present. Associate, 2004-08.
  • Law Clerk to the Honorable Arthur I. Harris, United States Bankruptcy Court for the Northern District of Ohio, 2002-04.
  • Judge Advocate; United States Marine Corps, 1998-2002.



Derek and his wife have three children and live in Avon, Ohio.

  • Successfully obtained appellate reversal of $2.4 million judgement against oil-and-gas company, which had resulted from failed sale of mineral interests. Atlas Noble, LLC v. Krizman Enters., 692 F. App'x 256 (6th Cir. 2017)
  • Obtained appellate reversal of order granting plaintiff’s motion for class certification in case involving allegedly improper practices for towing automobiles. Safi v. Central Parking System of Ohio, Inc., 45 N.E.3d 249 (Ohio Ct. App. 2015)
  • Defeated class certification and obtained summary judgment in RESPA case of national precedent, which invalidated long-standing HUD policy statement relating to affiliated-business arrangements. Carter v. Welles-Bowen, Inc., 736 F.3d 722 (6th Cir. 2013)
  • In groundbreaking case, successfully recovered seven-figure class-action defense costs from title agency after jury trial in Texas federal court.
  • Defeated class certification in two suits alleging that Fidelity National Title Insurance Company and Chicago Title Insurance Company had overcharged for title insurance policies in five different states.
  • Obtained complete dismissal of class-action claims against multiple real estate entities in Michigan lawsuit alleging improper collection of local taxes.
  • Successfully defended Ticor Title Insurance Company in a national class action seeking damages for alleged title insurance overcharges. Hazewood v. Found. Fin. Group, LLC, 551 F.3d 1223 (11th Cir. 2008)
  • Represented ExxonMobil Corporation in multi-district litigation involving “MTBE,” a fuel additive, for a mandamus action and a collateral‑order appeal from the district court’s plan to conduct bellwether trials.
  • Successfully defended on appeal €1.7 million judgment in favor of an Ohio software development company against a German company that breached a partnership agreement. Tharo Sys., Inc. v. cab Produkttechnik GmbH & Co. KG, 196 Fed. Appx. 366 (6th Cir. 2006)



Ohio State University, J.D., May 1998.

Honors and activities: Staff Editor, Ohio State Law Journal, 1997-98; Cali Award for Pretrial Litigation, 1998; Judge Joseph M. Harter Memorial Award for Trial Practice, 1997


John Carroll University, B.A., Political Science, magna cum laude, 1995

Memberships & Affiliations

American Bar Association: Member


American Land Title Association: Associate Member; Member, Best Practices Committee, 2016 to present; Member, State Advocacy Committee, 2016 to present


Cleveland Law Library Association: Board of Directors


Cleveland Metropolitan Bar Association: Bench-Bar Committee Member


Federal Bar Association, Northern District of The Ohio Chapter: Board of Directors and CLE Committee Chairperson


Real Estate Services Providers Council, Inc.: Associate Member; Member, Program & Education Committee, 2016 to present

Bar Admissions

Admitted to the Ohio Bar, 1998


Licensed to practice before the U.S. Supreme Court, U.S. Courts of Appeals for the Fifth, Sixth, Eighth and Eleventh Circuits and the U.S. District Court for the Northern and Southern Districts of Ohio

Awards & Distinctions

Ohio Super Lawyers, 2014-17


Ohio Rising Stars,” Ohio Super Lawyers, 2010-13


Distinguished Service Award, Standing Committee on Legal Assistance for Military Personnel, American Bar Association, 2001


Achievement Medal, U.S. Navy & Marine Corps, June 2000 (For service on Aviano Trial Team)


Award for Trial Advocacy, New York Bar Association, December 1999