William F. Dahill is a member of Dunnington’s employment, construction and litigation, arbitration and mediation practice areas. Since 1991, Mr. Dahill has concentrated his practice on complex commercial litigation and employment litigation and counseling. Areas of focus include securities industry litigation, employment litigation, payment processing disputes, asset purchases disputes, secured lending disputes, partnership disputes, shareholder disputes and construction litigation.

Mr. Dahill counsels and represents business entities at all levels and stages from start-ups to public companies. He also counsels and represents individuals in claims and defenses in litigation and employment matters. He appears regularly in Federal and State Courts in New York and Connecticut. Mr. Dahill is admitted to the bar in the States of New York and Connecticut, as well as to the bars of the Southern District of New York, Eastern District of New York, and the Courts of Appeals for the 2nd and 5th Circuits. In addition, he has appeared in jurisdictions throughout the country, including Northern District of Ohio, Pennsylvania State Court, Eastern District of Pennsylvania, Eastern District of Tennessee, Texas State Court, New Jersey State Court and Illinois State Court. Mr. Dahill conducts jury and bench trials, as well as appellate arguments. In addition, Mr. Dahill has conducted numerous arbitrations through full hearings at FINRA, AAA, JAMS and ARIAS. Finally, Mr. Dahill has substantial experience with successful mediations conducted both through the courts as well as private organizations.



  • Obtained FINRA arbitration award requiring securities firm to repurchase at par $100 million in illiquid municipal auction rate securities.
  • Successful bench trial obtaining an order directing that residuals held in escrow be distributed to Client; dispute arose over which secured party had priority to the residuals.
  • Jury trial in New Jersey State Court representing the plaintiff in an accounting malpractice action; successful settlement after openings.
  • Obtained arbitration award against seller of residuals for misrepresentation; obtained federal court award confirming the arbitration award and having that court pierce the corporate veil to have the award enforceable against the individual sellers.
  • Successful defense in AAA arbitration of “ahalife” from claims by a founder seeking one third of the company’s equity; claim withdrawn after one and a half days cross examination of claimant.
  • Representation of Lehman Brothers Specialty Finance in prosecution of claims against more than 100 major banks challenging ipso facto defaults declared on swap transactions after the Lehman Brothers bankruptcy filings, leading to substantial settlement recoveries for the Lehman estate.
  • Representation of family in BCL Dissolution proceedings for closely held business.
  • Successful motion to dismiss based on lack of personal jurisdiction over Connecticut based contractor sued in New York court.
  • Representation of Estate in a FINRA proceeding which recovered funds withdrawn from an investment account based on forged signatures.
  • Representation of an investment banker in an action seeking damages for breach of an oral contract and misrepresentation resulting in a multimillion-dollar judgment for the client, including an award of punitive damages, after a two-week jury trial in federal court in Bridgeport Connecticut.
  • Representation of a U.S. broker/dealer in 5-year arbitration, confirmation proceedings and appeals resulting in the denial of a multi-million dollar employment and whistle-blower claim and a defamation claim arising out of statements made in a Form U-5 as well as complex securities issues involving allegations of mispricing of illiquid investment grade, convertible and high yield bonds and the effect thereof on regulatory filings of the broker/dealer.
  • Representation of Swann Analytics in successful opposition through a preliminary injunction evidentiary hearing of a franchise termination dispute in federal court in New Haven.
  • Representation of family in successful FINRA arbitration claims and subsequent confirmation and appeal affirming a $3.5 million arbitration award against a securities broker.
  • Representation of Art Capital Group in successful litigation enforcing secured lender’s rights against Annie Leibovitz.
  • Representation of a nursing home, Ruby Western Manor, in $30 million dispute with the general contractor and eighteen subcontractors involving delays, cost overruns and costs to complete; reached a favorable resolution after three weeks of jury trial in Brooklyn.
  • Representation of Michael Page International in multiple matters, including matters successfully enforcing non-competes in which injunctive relief has been obtained and payments made by adversaries.
  • Representation of individuals and entities in connection with formal and informal investigations by the SEC and the New York State District Attorney’s office on securities-related matters.
  • Representation of Westinghouse Air Brake Technology Company in asbestos personal injury cases brought by New York Transit Authority employees; successfully obtained summary judgment in multiple matters.


Mr. Dahill represents clients with offices and facilities nationwide, including defending claims brought for various forms of alleged discrimination, including gender, sexual harassment, sexual preference, religion, age, national origin, and disability. Fora include federal and state courts, state human rights commissions, and arbitration. Practice also includes advice on terminations, force reductions, enforcing restrictive covenants, and claims asserting breaches of restrictive covenants.

Recent Examples

  • Dismissal of claims alleging discrimination due to disability filed in Connecticut Human Rights and Opportunities commission.
  • Obtained arbitration award dismissing claims against company for gender discrimination, sexual harassment, and retaliation.
  • Representation of Mankraft Corp. in a successful bench trial of alleged discrimination claims in Pennsylvania State Court, Philadelphia.
  • Obtained favorable settlement on behalf of company after two days of arbitration of claim for religion and national origin discrimination.
  • Successful negotiations with New York Attorney General’s office concerning claims alleging violations of disability laws.
  • Successful negotiation with New York City Department of Consumer Affairs concerning alleged violations of Sick Leave Law.
  • Successfully defeated an effort to enforce restrictive covenants against very highly compensated investment bankers.
  • Successfully enforced restrictive covenants preventing use of misappropriated proprietary and confidential information.
  • Representation of a major supermarket chain in connection with claims asserted by the Department of Labor under the Fair Labor Standards Act for the alleged failure to pay overtime wages.


Mr. Dahill received his J.D. from Fordham University School of Law, cum laude, in 1991, where he served as Managing Editor of the Moot Court Board. Mr. Dahill received his B.A. in Architecture from Columbia University in 1984.


  • Federal Bar Association, Past President of the SDNY Chapter (2013-2014) and current Executive Committee Member.
  • Network of Bar Leaders, Executive Council.
  • New York City Bar, Member Professional Discipline Committee, Member Litigation Funding Working Group.
  • Attorney Grievance Committee for the First Department, appointed 2019-2022.
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