Marisa O’Sullivan
Main image for Marisa O’Sullivan

Marisa O’Sullivan

Clients count on me to distill complex problems, deliver practical advice, position them optimally, and achieve outstanding results. My ability to identify pressure points and negotiate advantageous resolutions has enabled me to skillfully advocate for those I represent over the course of my career.

Providing pragmatic, business-focused counsel in her national practice, Marisa O’Sullivan focuses on insurance recovery for commercial policyholders. She draws on her experience and excellent strategic thinking skills to guide clients through large-scale litigation and arbitrations that maximize recoveries. In addition, Marisa assists in the preparation and presentation of complex claims and proofs of loss. She also facilitates claim dispute resolutions with insurers prior to litigation when that’s the best path forward.

On the advising side, Marisa analyzes insurance programs and individual policies to identify holes or overlaps in coverage, make sensible policy recommendations, and accomplish risk transfer objectives. She also scrutinizes the interplay between the client’s insurance policies, the policies maintained by vendors and contractors, and the insurance and indemnity provisions in contracts.

In particular, Marisa has a wealth of experience with cyber insurance and related cyber risks. She adroitly provides cutting-edge counsel on coverage for security breaches, system failures, privacy events, and reputational damage. As cyber concerns recur in the nightmares of corporate leadership everywhere, Marisa offers steady guidance on risk management and claim response to help them weather the storms.

From the outset of any project, Marisa evaluates her client’s ultimate objectives and works diligently to achieve them, whether through favorable contractual terms, preferable resolution of a claims-track dispute, or settlement of coverage litigation. She enjoys the intellectual challenge of devising creative strategies in insurance coverage disputes, which she compares to chess matches.

With a career spent entirely immersed in the insurance coverage arena, Marisa is frequently asked to write and speak on insurance topics. She has garnered several peer-nominated awards for her professional achievements. Marisa’s depth of experience in insurance recovery and long-standing reputation within the specialty produce the credibility that insurers respect and the type of outcomes clients want.

Outside of her work for clients, Marisa consistently receives recognition from her colleagues and peers for her leadership in the Dallas legal community. She currently serves as the Dallas Women Lawyers Association (DWLA) President. Named by the Dallas Association of Young Lawyers (DAYL) Outstanding Young Lawyer of the Year in 2019, Marisa is a DAYL Foundation and Dallas Bar Association (DBA) Foundation Fellow, and currently serves on the boards of the DBA and DWLA Foundation.

Significant Matters

Litigation Experience

  • Represented a travel technology company in coverage litigation against its commercial general liability and errors and omissions insurers to recover $90 million in policy limits for the defense and settlement of an antitrust lawsuit; settled after a favorable ruling on motion for summary judgment.
  • Represented a national seafood distributor in high-stakes coverage litigation to secure reimbursement for an eight-figure inventory loss.
  • Engaged by a national alarm monitoring company as insurance coverage counsel in negotiations to settle a class action MDL seeking $40 billion in damages for violations of the Telephone Consumer Protection Act; represented the client in resulting coverage litigation against cyber and commercial general liability insurers in Texas and West Virginia; ultimately negotiated separate settlements with each insurer, including complex indemnity provisions.

  • Represented a bar and restaurant in securing coverage for a multimillion-dollar personal injury claim; secured a summary judgment on the duty to defend and 100% insurer-funded settlement of the underlying case.
  • Represented a publicly traded heating, cooling, and refrigeration manufacturer in coverage litigation against its first-layer excess insurers related to a $100 million insurance program providing coverage for a nationwide asbestos docket; ultimately negotiated a favorable cost-sharing agreement with the excess carriers.
  • Represented an aerospace manufacturer in coverage litigation against its commercial property insurers for $30+ million in business interruption losses resulting from hurricane-related flooding.

Claim Negotiation + Advice Experience

  • Advised an international retailer on coverage issues to favorably structure a business income loss claim under a commercial property policy for losses sustained by its Puerto Rico properties following Hurricane Maria.
  • Completed a comprehensive cyber policy analysis for an airline client, including a comparison of 30+ risk scenarios against cyber policy language and recommendations to resolve gaps in policy language.
  • Engaged by a global telecommunications technology company to challenge denials from cyber, commercial general liability, and directors and officers insurers for defense costs related to a series of high-stakes patent infringement and unfair competition lawsuits; secured insurer payment of millions in defense costs without coverage litigation.
  • Completed a cyber insurance program assessment for a governmental entity, including participation in risk roundtables with engineering, IT, marketing, and operations department heads to identify risks; analyzed insurance and indemnity requirements in cybersecurity vendor contracts; and made recommendations to client and broker teams regarding cyber policy language.
  • Advised a Fortune 500 retailer on coverage issues under cyber and commercial general liability policies (both as a named insured and as an additional insured) in connection with a multistate MDL consumer class action; analyzed class action settlement insurance policy; and challenged the insurers’ coverage positions on various issues.
  • Engaged by multiple real estate developer clients to assist with claims track negotiation related to business income losses and large-scale property damage due to flooding, winter storm damage, fire, and COVID-19-related losses.

Areas of Focus



  • Southern Methodist University, Dedman School of Law (J.D., cum laude, 2012)
    • Chief Counsel for the W.W. Caruth Child Advocacy Clinic, Fall 2011
    • Jackson Walker Moot Court, Board Member
  • Honors College at the University of Missouri (B.A., magna cum laude, 2009)
    • Study Abroad Exchange, University of Manchester, United Kingdom, Spring 2008
    • Study Abroad, Ghana, West Africa, Winter 2007


Bar Admissions
  • Texas
Court Admissions
  • U.S. District Court, Northern District, Texas
  • U.S. District Court, Eastern District, Texas
  • U.S. District Court, Western District, Texas


  • Rainbow Days Pot of Gold Luncheon Chair, 2022
  • East Dallas Developmental Center
    • Board Member, 2021-present
  • Dallas Association of Young Lawyers
    • Board Member, 2017-2020
    • Member, 2012-present
    • Leadership Class and Project Steering Committee Member, 2015-2016
    • Membership Chair, 2012-2015
  • Dallas Women Lawyers Association
    • President, 2022
    • Board Member, 2017-present
    • Mentoring Circles Steering Committee Co-Chair, 2015 -2019
  • Dallas Women Lawyers Association Foundation
    • Board Member, 2021-present
  • Dallas Bar Association
    • Board Member, 2021-present
    • Trial Skills Section, Board Member, 2015-2016
    • Tort and Insurance Practice Section, Board Member, 2015-2016
  • National Women Lawyers Association
    • Rising List, 2022
    • Dallas Conference Steering Committee Member, 2017-2018
  • Fellow: Dallas Association of Young Lawyers Foundation
  • Fellow: Dallas Bar Association Foundation
  • Junior League of Dallas, Member, 2014-2017


  • Lawdragon 500, Leading Litigators in America, Commercial Litigation - Insurance Coverage Litigation, 2024
  • Irish Legal 100, 2023
  • Texas Women Lawyers, Brenda Tso Rising Young Lawyer Award, 2023
  • Best Lawyers in America: Ones to Watch, 2022-2024, Commercial Litigation; Insurance Law
  • Named to the Texas Super Lawyers list, as published in Texas Monthly magazine, 2023
  • Selected as a Texas Rising Star by Super Lawyers, as published by Thomson Reuters (2018-2022)
    • Up and Coming Women Top 50, 2022
    • Up and Coming Top 100, 2022
  • Named one of the Best Lawyers in Dallas in Insurance Law by D Magazine (2021-2024)
  • Named one of the Best Lawyers in Dallas Under 40 by D Magazine (2019-2024)
  • National Association of Women Lawyers, Rising List (2022)
  • Named Outstanding Young Lawyer by the Dallas Association of Young Lawyers (2019)
  • Selected by the Dallas Association of Young Lawyers as One to Watch (2016)

    Best-Lawyers-Logo (1)



  • Necessary Evils - Insurance Edition, Carrington Coleman Capital Newsletter, 2023 Industrial & Other Real Estate Issue, author, February 2023.
  • Solving Cybersecurity: How to Help Your Client Navigate the Minefield, panel presentation to Dallas Association of Young Lawyers, In-house Counsel CLE, Dallas, Texas, August 2019.
  • Nuts & Bolts: Directors & Officers Liability Policies, article for Journal of Texas Insurance Law, Volume 15, Number 1, August 2017.
  • Insurance 101: What Every Young Lawyer Should Know, presentation for Dallas Association of Young Lawyers, Dallas, Texas, November 2016.
  • E-Discovery: What it Means to Us, article for TYLA eNews, a Texas  Young Lawyers Association publication, April 2016.
  • E-Discovery Outsourcing, presentation for Global Society class, Sociology Department, Southern Methodist University, Dallas, Texas, November 2015.
  • Mistakes in Corporate Insurance: The Top 10, article for Headnotes, a Dallas Bar Association publication, June 2015.
  • E-Discovery Outsourcing, presentation for Global Society class, Sociology Department, Southern Methodist University, Dallas, Texas, April 2015, November 2014, and April 2014.
  • The Skinny on Dodd-Frank for Insurance Counsel, article for Consultant’s Corner for, February 2015.
  • The Top Ten Corporate Insurance Pitfalls for Counsel to Avoid, article for Consultant’s Corner for, January 2015.
  • Taking Inventory: An Overview of Corporate Liability Insurance, article for Consultant’s Corner for, December 2014.

Outside of Work

In addition to spending time with their children and their dog, Marisa and her husband enjoy traveling. Favorite destinations include the Napa Valley wine region and places where they can engage in outdoor adventures, such as Patagonia.