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Colleen Mary Prosser

also known as Colleen Sinclair Prosser

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About me

Possessing an extensive background in real estate law, she served several years as Counsel to Chicago Title Insurance Company of Washington, D.C. Currently the owner and manager of SinclairProsser Law, LLC, Colleen steers her firm with both a guiding hand and also direct involvement with SinclairProsser Law’s clients, bringing to the table a wealth of Estate Planning experience from several years spent at the helm of a busy practice. She has served on the Board of Governors Education Committee of the American Academy of Estate Planning Attorneys in the past.  Colleen is currently serving on the Board of Trustees for By Their Side, Lifelong Advocates for Marylanders with Developmental Disabilities.


Professional Experience

An established member of the American Academy of Estate Planning Attorneys, Colleen offers years of experience in estate preservation and transfer. Strong proponents of the living trust, she also focuses on wills, powers of attorney, living wills, probate, trust administration, prenuptial agreements, nursing home planning, and Special Needs planning. She strongly endorses long-term care insurance and, in certain cases, life insurance and some annuities as valuable estate preservation vehicles, and strives to assure the compatibility of her clients’ estate plan and financial plan. Sensitive to the challenges presented by lifestyle and circumstance, Colleen addresses each situation with personal attention, wisdom, and skill.



Colleen Sinclair Prosser received her Bachelor of Science degree with Academic Honors from University of Maryland, College Park, and earned a Juris Doctor degree from The Catholic University of America. She continues her legal education, teaches Continuing Education classes, and meets the education requirements of the American Academy of Estate Planning Attorneys by performing 36 hours a year. She is an approved IRA distribution attorney under the guidance of Ed Slott—a nationally recognized IRA distribution expert—and is a member of the Maryland and District of Columbia Bar.



One of five children, Colleen was born in Washington, D.C. and is a lifetime resident of Maryland. She is the daughter of the late R. Ronald Sinclair, founder of SinclairProsser Law, LLC and executive member of the American Academy of Estate Planning Attorneys, and Maureen Mershon, partner in the Holiday Point Marina in Edgewater, Maryland. Ms. Prosser is married to award-winning artist Les Prosser, Jr. Colleen and Les are the proud parents of one son, Jake. They frequently camp in the surrounding mountain ranges and parks and make an annual trip to the Adirondack Mountains of New York. Colleen also enjoys the Arts and has a fondness for British culture cultivated by her time as an exchange student in Europe.


Photos and videos

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Practice areas


  1. Probate: 60%
    22 years, 200 cases
  2. Estate Planning: 40%
    22 years, 1 thousand cases



Fixed (always)

Payment types:

Cash, Check, Credit card

Attorney endorsements

9 total 

Are you an attorney? Endorse this lawyer

  • Catherine Hammond

    I have known Colleen for a number of years through our mutual membership in the American Academy of Estate Planning Attorneys. She is truly a leader among her Academy colleagues in technical expertise and her guidance is regularly sought from a legal perspective. However, it is her fierce commitment to her clients and their best interests that I most admire. I highly recommend Colleen and her firm.


    Catherine Hammond Estate Planning Attorney
    Relationship: Fellow lawyer in community

  • Shawn Garner

    I endorse this lawyer.


    Shawn Garner Estate Planning Attorney
    Relationship: Friend

Contact info

SinclairProsser Law, LLC

900 Bestgate Road
Suite 103
Annapolis, MD, 21401

SinclairProsser Law, LLC

8530 Veterans Highway
2nd floor
Millersville, MD, 21108

SinclairProsser Law, LLC

14300 Gallant Fox Lane
Suite 204
Bowie, MD, 20715

SinclairProsser Law, LLC

603 Post Office Road
Suite 306
Waldorf, MD, 20602



DCActive 199105/25/2015
We have not found any instances of professional misconduct for this lawyer.
Avvo contributions
Legal answers
Work experience
TitleCompany nameDuration
Board MemberBy Their Side2002 - Present
Attorney/OwnerSinclairProsser Law, LLC1996 - Present
Association namePosition nameDuration
The District of Columbia BarN/A1991 - Present
Maryland State Bar AssociationN/A1990 - Present
American Academy of Estate Planning AttorneysN/AN/A
Anne Arundel County Bar AssociationN/AN/A
National Academy of Elder Law AttorneysN/AN/A
Legal cases
Case nameOutcome
Estate of Rebecca BednarikSettlement of Probate Estate
See all legal cases 
Publication nameTitleDate
American Academy of Estate Planning AttorneysTotal Wealth Management2004
School nameMajorDegreeGraduated
Catholic University of America, Columbus School of LawLawJD - Juris Doctor1990
University of Maryland, College ParkN/ABS - Bachelor of Science1985
Speaking engagements
Conference nameTitleDate
Estate Planning Seminar for Non-Profit OrganizationsWhat is Planned Giving?2011
2011 Quarterly Membership MeetingLegal Issues for Families and Individuals with Intellectual & Developmental Disabilities2011