Colleen M O'Neil

Practice Areas

Litigation

Business, Corporate and Commercial Litigation

Probate Litigation

Public Law Litigation

Health Care Litigation

Labor and Employment Litigation

Appellate Proceedings Litigation

Real Estate Litigation

Professional Memberships

Cleveland State University College of Law Board of Visitors, Member

Irish American Law Society of Cleveland, Founding Member, Former Vice President

In Counsel With Women, Member

Cleveland State University College of Law Alumni Association, Board Member

Leadership Cleveland Class of 2016

Cleveland Metropolitan Bar Association, Member

Ohio State Bar Association, Member

American Bar Association and the ABA’s Litigation Section, Member

Experience

Representative Business, Corporate, and Commercial Litigation Matters:

Serving as lead counsel to an American publicly traded, Fortune 1000, multinational company in a contract and trade secret dispute arising from a previous commercial relationship between the client and a manufacturer based in the Northwest U.S., involving one of the client’s products. The client filed a complaint against the defendant in United States District Court asserting claims for declaratory judgment and breach of implied duty of good faith and fair dealing. A few weeks later, the defendant filed its answer including counterclaims for breach of contract and misappropriation of trade secrets under state law. After discovery commenced, it became clear that the defendant had fraudulently induced and/or breached the contract in a myriad of respects resulting in the client amending its Complaint on two separate occasions to reflect the defendant’s wrongdoing.

Serving as lead counsel to a national medication prescription services provider in a proposed class action against them for alleged violations of the Telephone Consumer Protection Act (TCPA). The plaintiff alleges wrongful telephone solicitation of the plaintiff and persons similarly situated in violation of the TCPA and in contravention of the National Do Not Call registry. The client vehemently denies the allegations as it has an extensive TCPA compliance program, and the client asserts that the specific plaintiff provided express consent to the phone solicitation, and therefore both the plaintiff’s claims and the attempted class action certification are meritless.

Served as lead counsel for a municipality in Ohio in a tax litigation matter involving a school district that commenced litigation alleging that the city was in violation of an agreement to share a municipal income tax with the school district. (2024)

Served as lead counsel in this “bet-the-company” case involving corporate and governance disputes between the Co-Trustees of a family trust that owns a manufacturing and distribution company. Calfee represents the Trustee and shareholder of the client company, who asserted claims for breach of fiduciary duty, declaratory judgment, and allegations of self-dealing against the Co-Trustee after more than a decade of unchecked malfeasance. The claims Calfee brought on behalf of its client sought court intervention to require the Co-Trustee to employ governance and compliance mechanisms to the Trust’s most significant asset, the family company. The defendant Co-Trustee asserted mirror counterclaims yet denied any obligation to employ standard corporate governance procedures to ensure the continued viability of the family owned company. Calfee’s role was to strategize and resolve the impasse as to corporate governance that would set the foundation for the future success of the company and the growth of the Trust assets.

Representative Labor and Employment Litigation Matters:

Served as counsel for Defendants, a multi-billion-dollar, international construction company in a matter in which the Plaintiff company brought several claims, including breach of duty of loyalty, breach of contract, conspiracy, misappropriation of trade secrets, and interference with prospective business relationships, against (1) two members of a group of its former employees who quit and joined its competitor, Calfee’s client, (2) Calfee’s client company, and (3) a member of the client company’s management team. Upon being served with the Complaint, Calfee mobilized its client’s response to preserve electronic data, seizing all relevant company-issued electronic devices in the possession of Plaintiff’s former employee. Calfee’s clients moved to dismiss the Amended Complaint and the court dismissed five of Plaintiff’s Claims against the client company and dismissed the client management team member from the lawsuit entirely. With just the destruction of evidence and misappropriation of trade secrets claims still pending, the parties engaged in discovery and began taking depositions. Subsequently, the parties signed a settlement agreement in which Calfee’s client paid nothing, there was no confidentiality provision (meaning Calfee’s client was free to discuss the case with its customers), and the lawsuit was dismissed.

Expert in these Jurisdictions

Ohio

Career

Colleen O’Neil serves as Co-Chair of Calfee's Litigation practice group. She helps clients resolve complex business disputes, and she has extensive experience in federal and state courts nationwide helping business clients resolve the following:

Commercial contract disputes

Shareholder and corporate disputes, including post-closing issues

Estate and probate matters

Trade secret claims

Real property disputes

Municipal and public law issues

Title VII claims

Colleen has counseled and represented businesses, financial institutions, and high-net-worth individuals in a variety of corporate, commercial, fiduciary, and employment disputes with a results-oriented, practical approach.

She has successfully prosecuted and defended a variety of business tort claims in both federal and state courts nationwide.

Colleen has represented municipalities and clients in the energy industry in various types of litigation, including contractual disputes, real estate disputes, and employment matters.

Colleen has been selected for inclusion in the Ohio Super Lawyers list (2012-2025) and in the Top 50 Women Attorneys in Ohio list.

Colleen joined Calfee in 1998, and she is a member of the firm’s Diversity, Equity & Inclusion Committee. Colleen began serving as Vice Chair of the firm's Litigation practice group in 2019 and Co-Chair in 2021.

Education

Awards