Gregg W. Mackuse

Partner Philadelphia
Phone: (215) 988-2550
Fax: (215) 988-2757


Gregg W. Mackuse has spent over two decades prosecuting, defending and monitoring complex matters in virtually the entire spectrum of complex commercial litigation. He has monitored and participated in multi-state litigation against individuals and entities, including banks, investment advisers and outside professionals.

Gregg also has conducted internal investigations and prepared analyses of possible corporate misconduct by management and outside professionals. In federal multidistrict litigation, he has assisted in monitoring and oversight of hundreds of claims in connection with a nationwide class action settlement.

Gregg’s experience with complex health care fraud litigation involves extensive document discovery, substantial fact and expert discovery, and detailed motion practice throughout the United States. He has represented a pharmaceutical manufacturer for many years and successfully litigated numerous complex insurance recovery matters.


Gregg served as trial counsel in state Attorney General litigation asserting violations of the state Medicaid fraud false claims act statute and deceptive trade practices act. He was also co-counsel in matters including:

  • Co-counsel in proposed class action against health insurance company asserting claims for violation of Pennsylvania Non-Profit Law, breach of contract and breach of fiduciary duty. Pennsylvania Supreme Court reversed intermediate appellate court’s dismissal of action.
  • Representation of two former employees in health care fraud litigation under Federal False Claims Act. The action involved millions of pages of documents, more than 100 fact and expert witnesses, numerous discovery disputes, and extensive motion practice and trial preparation. Following extensive mediation, the matter resulted in substantial settlement.

Gregg has defended a pharmaceutical manufacturer in multiple state court actions against claims of common law fraud, Medicaid fraud and violations of state deceptive trade practices acts. He also represented a pharmaceutical manufacturer in class action civil RICO suit brought by third-party payors.

Gregg also served as co-counsel in a successful appeal of an Attorney General action asserting violations of a state Medicaid fraud false claims act statute and deceptive trade practices act.

Gregg successfully represented a corporate client seeking the recovery of defense costs from an insurance carrier under a directors’ and officers’ (D&O) liability policy. He has represented several state insurance commissioners in multi-stage litigation involving brokers, investment advisors, and financial institutions. Matters include:

  • Representing state insurance commissioner in multistate litigation handling and monitoring numerous litigations involving broker and investment adviser liability, lender liability, professional liability and fraudulent conveyances in effort to recover millions of dollars in assets. Representation included conducting internal investigation of corporate records and employees and the preparation of detailed legal analyses concerning proposed litigation.
  • A multi-year massive professional liability action on behalf of state insurance commissioner against former managing general agent and its parent company, encompassing virtually every aspect of the insurance industry including underwriting, primary and excess coverage, actuarial services and claims handling. Matter was resolved for a total settlement of $51.6 million.
  • Representing the Insurance Commissioner of the Commonwealth of Pennsylvania, as statutory liquidator for an insolvent insurer, successfully challenging actions by a financial institution seeking to set-off, as counterclaims and affirmative defenses, alleged debts of an agent of the insolvent insurer against tort claims of the statutory liquidator.
Gregg successfully represented a major academic institution in the recovery of defense and settlement costs for class action based on two of its research studies.


Bar Admissions

  • New Jersey
  • Pennsylvania


  • Villanova University School of Law, J.D., 1988, cum laude, Order of the Coif
  • University of Pennsylvania, 1984

Court Admissions

  • U.S. Supreme Court
  • U.S. Court of Appeals, Second Circuit
  • U.S. Court of Appeals, Third Circuit
  • U.S. Court of Appeals, Sixth Circuit
  • U.S. District Court, Western District of Michigan
  • U.S. District Court, District of New Jersey
  • U.S. District Court, Eastern District of Pennsylvania
  • U.S. District Court, Middle District of Pennsylvania
  • New Jersey Supreme Court
  • Pennsylvania Supreme Court

Gregg's Areas of Focus