This collection consists primarily of legal papers, which include court issued "writs" (legal forms) serving notice to named defendants to answer to charges brought by plaintiffs against them, writs of execution enforcing a judgment, or writs summoning parties to the Court of Common Pleas, on appeal from the decisions of the Justice of the Peace.

Some of the writs use the officially named causes of action (such as "Writ of Debt," "writ of Scire Facias" etc.) based upon the highly technical English common law system of the 17th and 18th centuries. However, primarily due to relative scarcity in the English colonies of lawyers and judges formally trained in the English common law system, choice of the proper cause of action became much less important. Thus, a great number of the writs in this collection are writs of "trespass," or "trespass on the case," or "case," the "catch-all" cause of action, even though the actual suit might be for debt, assault, or any other situation. A few, however, such as "Writ of Scire Facias" (show cause why judgment has not been executed), "trespass" (describing a true trespass), "assault vi et armis," and "Trespass quare clasusum fregit" (why a "close" was broken for trespass), are appropriately named. Other complaints are informally written, not naming a particular cause of action, but simply stating the situation and the case against the named defendant.

This collection provides researchers of early American law with the forms of litigation in the middle and late 18th century, the types of causes most commonly brought before the local justices of the peace, and the American simplification of the English common law system.

The collection has been organized into two series.

Series I. Legal Papers and Memorandum Books contains the litigation documents described above, arranged chronologically. It also contains three personal books, one of which is a hand written treatise of memorandum by Parsons on the laws and jurisprudence of England, its government, judicial systems and religious institutions past and present, as well as a description of the city of London, including its population, environs, colleges, and monuments. European currency past and present, weights and measure, and various other subjects are all carefully inscribed in a miniscule hand. It is not possible to ascertain which of the passages are copied from other sources, which written by Parsons himself. Some portions are attributed to various sources; notes on European currency have been copied from "Chambers Dictionary;" notes on famous persons from "Martin's Biographia Philsophia."

Series II. Oversize Legal Papers contains papers that do not fit into standard document boxes.