For-profit and nonprofit health plans and health services organizations have long relied on attorney Mark Mosby for interpreting federal and state health care and insurance regulations, oversight, and reporting requirements.

In what is part of a growing health care industry trend—assessing what specific elements make certain health care organization consolidations more successful than others—Mark’s insights, gained over his over 25 years of experience as general counsel and in private practice, are particularly valuable.

Currently, Mark serves as chief legal counsel to a regional health insurer located in Massachusetts, which has more than 1,200 employees, focused largely on government health insurance programs (Medicare, Medicaid, and dual eligibles). This client is also a health care provider that operates five Program for All-Inclusive Care for the Elderly (PACE) centers.

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Mark’s skilled counsel, pragmatic approach, and strategic thinking have been vital to the client in an industry that demands agility and responsiveness on very complex and important matters. The client has looked to Mark to work on an expansive range of transactional, contractual, regulatory, governance, and provider/vendor dispute-related problems.

Mark began his career as an associate in a commercial litigation law firm, followed by a Deputy General Counsel position at a state bar association, followed by five years as an attorney for the Illinois Supreme Court, and then as in-house counsel (Director and Deputy General Counsel positions) for several national and regional health plans for the next 20 years before joining Epstein Becker Green.

In addition, Mark presents on health law topics for the Illinois State Bar Association’s CLE program and other organizations.

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Focus Areas


  • Represented a Massachusetts-based health plan against payment demands for claims reimbursement made to the client. Mark conducted a fact-intensive review of the allegations and formed a defense that the facts and law do not support the demand. In terms of cost avoidance, Mark saved the client over $10 million in two years associated with such payment demands for claims reimbursement.
  • Determined whether a regional health plan was obligated to pay the ACA health insurer provider fee. Mark organized and worked with a national accounting firm and a tax attorney to determine that the client was exempt from the ACA tax. The client avoided a $7.5 million tax obligation.
  • Oversaw the sale and voluntary dissolution of an affiliated organization of a regional health plan operated as a joint venture. Mark led the preparation of extensive documentation associated with sale of the home health care business and performed the extensive wind up of the affairs of the business that took almost three years.
  • Resolved a dispute involving a Massachusetts-based health plan and its joint venture partner who refused to reimburse the client for an additional capital contribution to the joint venture that was owed by the partner. Mark prepared a promissory note and issued a default notice to client’s partner. The client received a promissory note payment of over $1.1 million including interest and a late payment charge penalty.
  • Organized a 14-member legal department as Deputy General Counsel of a Michigan-based health plan. Mark focused on improving employee engagement and received recognition for leading a corporate department that had among the highest Gallup scores for employee engagement. At a result, it is a highly functioning legal department for one of the largest and most highly rated provider-owned health plans.



  • Washington University in St. Louis School of Law (J.D., 1985)
  • University of Virginia (B.A., 1982)

Bar Admissions

Court Admissions

Professional & Community Involvement

  • American Health Lawyers Association
  • Chicago Bar Association
  • Illinois State Bar Association, Health Care Section Council
  • Spiritual Life Council, Eckerd College, St. Petersburg, Florida



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