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Mary-Claire Petcoff

  • p. 248.642.0333 ext. 340
  • Email


Mary-Claire Petcoff focuses on divorce and family law issues, with additional work in real estate and litigation.

While pursuing her Juris Doctor at the University of Maryland, Mary-Claire developed a strong interest in family law and supplemented her classroom learning by clerking for an Annapolis circuit court judge over a two-year period. In addition to general civil and criminal cases, the judge oversaw a busy family law docket, giving Mary-Claire ample opportunity to research, draft, and debate opinions in a wide variety of domestic relations cases. Because of her intellect and strong work ethic, the judge asked her to coordinate membership efforts for the National Courts & Sciences Institute, an organization of jurists devoted to studying the impact that addiction, domestic abuse, and emotional wellbeing has in divorce and child custody disputes.

After law school, Mary-Claire relocated to Michigan, where she joined a small general practice firm and quickly began to take on her own divorce cases and clients. She brought her talents to Williams, Williams, Rattner & Plunkett at the beginning of 2018, and continues to gain experience in high-asset divorces and separations, division of property and business assets, spousal and child support, and child custody disputes. She has even leveraged her French language skills (she has additional proficiency in Russian and Spanish) to help counsel a dual U.S-French citizen in a divorce matter in France.

Outside of the office, Mary-Claire has a passion for cooking and baking, is an avid reader, and loves to travel, both domestically and around the world.

Professional Affiliations

  • State Bar of Michigan
    • Family Law Section
  • Oakland County Bar Association

Community/Civic Activities

  • Anne Arundel County Board of Elections
    • Chief Election Judge, April-November 2014 and April-November 2016


  • Michigan, 2017


  • Law Clerk to the Hon. Ronald A. Silkworth, Circuit Court for Anne Arundel County, Maryland, 2016

Practices ›

Education ›


  • University of Maryland Francis King Carey School of Law, Juris Doctor, 2016
    • Certification in Transformative Mediation
  • Bucknell University, Bachelor of Arts in History, cum laude, 2013
    • Minors in International Relations and French
    • Community Judicial Board
    • Equestrian Team
    • Certified by the Diplôme d’étude en langue française (DELF), level B2