LAWYER
Diane Siegel Danoff
Partner | Philadelphia
Diane Siegel Danoff

Diane Siegel Danoff is a nationally recognized litigator in our Intellectual Property Group and heads the group’s award-winning, global Trade Secret Litigation practice. She has extensive litigation experience, developed during over 35 years of practice, with trade secret, non-compete, trademark, patent, copyright, unfair advertising, and invasion of privacy matters. Ms. Danoff frequently handles injunctions and, in one case in federal court, won a highly unusual award of attorneys’ fees at the temporary restraining order stage of the case.

Ms. Danoff has been named more than ten times as a leading litigator by Chambers USA, a referral guide to leading lawyers in the United States. Most recently recognized in 2024 for Intellectual Property in Pennsylvania, Chambers has previously called her “superb, thorough and decisive” and “recommended for her courtroom skills.” Since 2023, she has been recognized as a “World’s Leading Trademark Practitioner” in World Trademark Review’s WTR 1000. In addition, she is listed in The Legal 500 US, is recognized by The Best Lawyers in America 2025 for Intellectual Property and Patent Litigation, and in 2017, earned the "Lawyer of the Year" distinction for Trade Secrets law. In 2015, Ms. Danoff was named a BTI Client Services All-Star, recognized as one of 25 IP lawyers nationwide for excellence in client service and “having a deep awareness of the interplay between the complicated technical, legal and business issues facing IP clients.” Since 2020, she has been named an "IP STAR" for both trademark and copyright by Managing Intellectual Property.

Ms. Danoff was awarded the Arthur Seidel Distinguished IP Service Award by the IP Law Institute of the Pennsylvania Bar Institute in 2017.  

Ms. Danoff maintains an active pro bono practice, including voting rights litigation. She represented LatinoJusticePRLDEF and Nueva Esperanza Inc. in the Voter ID litigation in Pennsylvania and represented the Texas State Conference of the NAACP and the Anti-Defamation League Southwest Region in ballot access litigation in Houston.

Ms. Danoff is a member of the Board of Directors of WHYY (an NPR affiliate) and the Philadelphia regional board of the Anti-Defamation League. She is a past chair of the board of Philabundance, a hunger relief non-profit.

  • Represented Microsoft Corp. and a prospective Microsoft executive in a non-compete/trade secret litigation by an international technology company against the executive. Resolved favorably.
  • Defending Tekni-Plex, Inc. in a patent, trade secret and trade dress case involving plastic tray technology used in products sold at Whole Foods, Trader Joe’s and other stores nationwide. Obtained invalidation of all challenged patent claims before Patent Trial and Appeal Board.
  • Represented Synthes (medical device company) in a trade secret and Lanham Act case. Resolved by a US$13.5 million payment to our client (and an agreement not to solicit our client’s employees) following a two-week jury trial.
  • Obtained preliminary injunction for WebMD following four-day evidentiary hearing in trade secret and non-compete case involving former high-level executive.
  • Represented Marriott International in trademark and false advertising counterclaims within antitrust litigation involving keyword advertising in the E.D. Texas. Case ended during jury trial in take-nothing settlement in favor of Marriott and public apology by plaintiff.
  • Defended SGS International Inc. in a US$25 million trade secret case in the M.D.Fla. involving alleged misappropriation of trade secret printing techniques in the making of Tervis Tumblers drinkware, obtaining voluntary dismissal before trial in complete walkaway, with no payment of damages or injunction.
  • Representing Atos and CNA Financial Corporation in a $132 million copyright litigation in the N.D. Texas.
  • Represented leading semiconductor packaging company in trade secret, copyright, and patent litigation in the District of Delaware, claiming over US$90 million in damages. Settled favorably.
  • Represented Chief Medical Officer hired by Bristol-Myers Squibb in non-compete/trade secret dispute with Novartis. Resolved amicably.
  • Defended Sheetz, Inc., a convenience store chain, in a litigation in the S.D. Ohio against the manufacturer of Splenda involving trademarks and the trade dress of dispensers for artificial sweeteners. Obtained amicable settlement.
  • Represented MetLife in business method patent case and separate trade secret action involving a method of funding insurance products. Obtained complete victory before trial court which was affirmed on appeal.
  • Represented Bank of New York Mellon in non-compete and trade secret litigation against former employee and investment advisory firm, in court and before FINRA. Settled favorably to our client.
  • Represented Alibaba in copyright and false advertising dispute.
  • Represented early-stage biotech company in expedited Delaware Chancery Court proceedings in trade secret litigation involving lentiviral vector technology.
  • Represented MicroGEM US in trademark/unfair competition litigation involving COVID-19 testing systems in the District of Utah. Obtained favorable settlement.
  • Represented Rohm and Haas, a subsidiary of Dow Chemical, in trade secret misappropriation case involving rheology modifiers for paint. Settled favorably to client with former employee agreeing not to work on the technology.
  • Defending Atos in software copyright litigation in the N.D. Texas.
  • Defended a major home shopping network in a trade dress and trademark litigation ending in a complete walkaway in favor of our client.
  • Represented Tribune Entertainment in non-compete case involving nationally broadcast program. Defeated plaintiff’s preliminary injunction motion following full evidentiary hearing. After that ruling, plaintiff dropped the case without any settlement.
  • Defended international package forwarding business in copyright/trade secret case alleging infringement and misappropriation of software. Settled favorably.
  • Represented life sciences consulting firm in trade secret and copyright litigation. Settled favorably to client.
  • Defended Dow Chemical Co. subsidiary in litigation arising out of a trade secret misappropriation litigation. Obtained complete dismissal by trial court and complete affirmances on appeal.
  • Represented Kellogg Co. and Nintendo in trademark/unfair competition suit involving a Pokémon® promotion on Kellogg’s® cereal boxes. Settled favorably to our clients.
  • Defended Hospice Care of Georgia, LLC in a trademark and false advertising case in the N.D. Georgia involving hospice names. Prevailed in preliminary injunction proceeding.
  • Won injunctions in employee non-compete/raiding cases for insurer Hilb Rogal, and Hamilton Co. (now part of Willis).
  • Defended Uptime Institute in trademark, false advertising and antitrust case in the D. Nevada involving data centers.
  • Representing Theia Technologies in a trademark litigation involving lenses used in high altitude drones and balloons, weather monitoring, and surveillance and security applications.
  • Defended European private equity firm in trademark litigation with major hedge fund in the U.S. District Court for the Southern District of New York.
  • Represented the leading U.S. dry pasta maker in Lanham Act case involving our client’s Ronzoni®, San Giorgio®, Prince® and Creamette® packaging. Settled favorably to our client.
  • Defended “Rocket Docket” patent/antitrust suit brought by Anheuser-Busch Companies against Crown Cork and Seal Co., involving aluminum can lids. Resolved by a Federal Circuit ruling for our client on certain counts and a settlement favorable to our client on the remaining counts
  • Represented Kofax in a false advertising case filed pursuant to the Lanham Act, and in companion trade secret/non-compete case, in the “Rocket Docket” of the U.S. District Court for the Eastern District of Virginia. Settled favorably to our client.
  • Defended WebMD in Lanham Act case regarding website publication. Settled favorably to our client.
  • Defended WPIX-TV in invasion of privacy litigation involving Public Service Announcement. Obtained voluntary dismissal without settlement following discovery.
  • Ms. Danoff has been recognized as an “IP STAR” by Managing Intellectual Property for her work in trademarks and copyright each year since 2020.

  • Ms. Danoff has been named ten times as a leading litigator by Chambers USA, a referral guide to leading lawyers in the United States.
  • Ms. Danoff has been recognized as a "Recommended Individual" by World Trademark Review's WTR 1000 rankings since 2023.
  • Dechert’s Trade Secret Litigation practice, which Ms. Danoff leads, was ranked Band 2 in World Intellectual Property Review’s inaugural “WIPR Insights 2023 Global Trade Secrets” Rankings.
  • Trade Secret Update, 2023 Technology Institute webinar (March 29, 2023)
  • 2023 IP Outlook, GC/CLO Summit — Association of Corporate Counsel for the Delaware Valley, Philadelphia PA (March 8, 2023)
  • Trade Secret or Patent Protection? — Managing Intellectual Property Intellectual Property & Innovation Summit U.S., New York City (May 24, 2022)
  • Recent Developments in the Law of Trade Secrets and Confidential Information — Association of Corporate Counsel for the Delaware Valley, Philadelphia PA (May 4, 2022)
  • Trade Secret Update, IP Law Institute — Pennsylvania Bar Institute, webcast (March 31, 2022)
  • Trade Secret Update, 14th Annual Intellectual Property Law Institute — Pennsylvania Bar Institute, webcast (July 28, 2020)
  • Lessons for Trade Secret Litigators from the Driverless Cars Space — American Intellectual Property Law Association (AIPLA) Annual Meeting, National Harbor, Maryland (October 24, 2019)
  • External Investigations: When is it Okay to Pretend? — Greater Philadelphia ACC (American Corporate Counsel) 11th Annual In-House Counsel Conference, Philadelphia, PA (April 24, 2019)
  • Trade Secret Update, 13th Annual Intellectual Property Law Institute — Pennsylvania Bar Institute, Philadelphia, PA (April 16, 2019)
  • Trading on Trade Secrets: What Financial Services Information is Protectable, Intellectual Property Issues in Financial Services Seminar: What's Hot? — Boston, MA (September 27, 2018)
  • Waymo v. Uber: DTSA Test Tube — IPO IP Chat Channel webinar, Intellectual Property Owners Association (March 15, 2018)
  • Lessons from the Waymo (Google)/Uber Self-Driving Car Case, For All Litigators — Greater Philadelphia ACC (American Corporate Counsel) 10th Annual In-House Counsel Conference, Philadelphia, PA (April 25, 2018)
  • Trade Secret Update, 12th Annual Intellectual Property Law Institute — Pennsylvania Bar Institute, Philadelphia, PA (April 24, 2018)
  • Trade Secret Update, 11th Annual Intellectual Property Law Institute — Sponsored by the Pennsylvania Bar Institute, Philadelphia, PA (April 26, 2017)
  • The New Federal Trade Secret Law and Other Recent Developments in the Law of Trade Secrets and Non-Competes — 22nd Annual Business Law Institute, Pennsylvania Bar Institute, Philadelphia, PA (November 16, 2016)
  • The Ethics of Pretexting in Investigations of Trade Secret Theft and Other IP Violations — Philadelphia Intellectual Property Law Association Year End Meeting, Philadelphia (May 3, 2016)
  • Trade Secret Update — Intellectual Property Law Institute sponsored by the Pennsylvania Bar Institute, Philadelphia (April 29, 2015)
  • Restraining Orders and Preliminary Injunctions — Commercial Litigation Institute sponsored by the Pennsylvania Bar Institute, Philadelphia (March 18, 2015)
  • Women in IP Law Breakfast panel on effective communications with clients — American Intellectual Property Law Association Spring Meeting, Philadelphia, PA (May 16, 2014)
  • Trade Secret Update, 8th Annual Intellectual Property Law Institute — Pennsylvania Bar Institute, Philadelphia, PA (April 8, 2014)
  • Protecting Your Trade Secrets Before It's Too Late — Association of Corporate Counsel - Greater New York Chapter, New York, NY (September 18, 2013)
  • Trade Secret and Non-Compete Update — DELVACCA, Philadelphia, PA (June 4, 2013)
  • Trade Secret Update — Philadelphia Intellectual Property Law Association, Philadelphia, PA (May 14, 2013)
  • Recent Developments in Trade Secret Law — Pennsylvania Bar Institute, Philadelphia, PA (April 25, 2013)
Services
    • Harvard University, A.B., 1981, magna cum laude, Phi Beta Kappa
    • The University of Chicago Law School, J.D., 1984
    • Pennsylvania
    • United States District Court for the Eastern District of Pennsylvania
    • United States Court of Appeals for the Third Circuit
    • United States District Court for the Northern District of Illinois
    • United States District Court for the Western District of Pennsylvania
    • Supreme Court of the United States
  • Ms. Danoff has served as a sub-committee Chair of the American Bar Association’s committee on Trade Secrets and Interference with Contracts and also the committee on Non-Compete Agreements.
     
    She has also served as a member of the Merit Selection Panel for the selection of a U.S. Magistrate Judge for the United States District Court for the Eastern District of Pennsylvania. 
     
    In addition, Ms. Danoff is a past Chair of the Board of Philabundance, a non-profit that gathers surplus food for the needy in the Delaware Valley.