James Mercer (February 26, 1736 – October 31, 1793) was a Virginia lawyer, military officer, planter, jurist and politician.

Thus James Mercer was born into the First Families of Virginia and received a private education suitable to his class, as well as access to his father's library, if not the best, then one of the best in the area.

At the time, Virginia had a primogeniture law so that landed estates passed to the firstborn son, clearly not James, as he knew in particular because his father was the guardian of and responsible for the education of his cousin George Mason, the firstborn son of George Mason III, who had died in a ferry accident.

[2] Although Virginia did not abolish primogeniture until 1785, either the apprenticeship changed James' career path or his father reconsidered, for soon (like his two elder brothers who survived infancy and are discussed below), he traveled to Williamsburg for higher education under prominent lawyer George Wythe and others, and graduated from the College of William and Mary about 1755.

His younger half brother John Francis Mercer would likewise become a planter and military officer (in the American Revolutionary War), but he married an heiress in Anne Arundel County, Maryland, where he would live, rise to become the state's Governor.

He also promoted the Chesapeake and Ohio Canal after this man's death (and became its president for a time), which also served the family's longstanding and ongoing western real estate interests.

[7] Unlike his brother James, George Mercer would only serve one term as a Burgess, possibly because he agreed to become a collector for the hated Stamp Tax in 1763 (though community pressure forced him to decline the position),[8] Complicating matters, James Mercer did not live in Hampshire County, but his family owned property there.

[9] Western Virginia counties had problems sending representatives to the legislature at Williamsburg, due to both the costs and time required to travel, as Daniel Morgan (who led a successful defense of Fort Edward in the French and Indian War before his heroics in the American Revolutionary War and legislative service from his Winchester base), well knew.

[16] Judge Mercer died in office in Richmond on October 31, 1793, about a year after his friend and fellow Ohio Company member George Mason.

Since his wife had died years earlier and their two daughters and one of their sons had not reached legal age, guardians were needed to administer his estate.