Mary Ann Van Ness brought a case against Cornelius P. Van Ness, administrator of John P. Van Ness, in the Supreme Court of the United States. Mary Ann was seeking to recover money from her late husband's estate which she claimed had been wrongfully withheld by his executor and administrator Cornelius. The court found that Mary Ann was entitled to receive $2,000 as part of her dower rights under Maryland law at the time of her marriage to John P., but that this amount had not been paid out due to an oversight on behalf of Cornelius when he settled the estate after John's death. As such, they ruled in favor of Mary Ann and ordered for payment from Cornilius' personal assets rather than those belonging to the deceased man's estate since it would be unjust for him or any other heirs who received their share already suffer loss due to negligence on behalf of another party involved with settling said estate.

In this case, Mary Ann Van Ness (plaintiff) brought a suit against Cornelius P. Van Ness (defendant), the administrator of her late husband's estate, John P. Van Ness. The plaintiff argued that she was entitled to an allowance from her husband's estate for support and maintenance during his lifetime as well as after his death due to their marriage contract which provided such allowances in the event of either spouse’s death or incapacity. The defendant contended that since no provision had been made for such an allowance in the will itself, it could not be enforced by law and thus should not be allowed under any circumstances. In dissent, Justice McLean argued that although there was no express provision in the will regarding these allowances, they were still enforceable because they were part of a valid marriage contract between two parties who had entered into it with full knowledge and consent prior to John P.'s death; therefore he believed that Mary Ann should have been granted her requested allowance from her husband's estate despite its absence from the will itself.