There, he befriended John Jay, Egbert Benson, Richard Harrison, Gouverneur Morris, and Robert R. Livingston – people who would become life-long friends in spite of political differences.

Eighteen months later, the Supreme Court of the province of New York changed the rules for admission to the bar lengthening the time period for a clerkship from five to seven years unless the clerk was a college graduate.

A top graduate of King's College, a former clerk of one of the most prominent lawyers of the day, and with the aid of retainers from Peter Silvester and his in-laws, he quickly developed a successful practice focusing on probate, debt collection, and disputed land titles.

Maxwell Bloomfield has noted that he developed the belief that “the insecurity of property rights in real estate transactions posed as great a threat to the welfare of the province as any of England’s tax measures.”[9] In November 1770, The Moot was established, which provided an opportunity for practitioners (senior and junior) to debate points of law with the aim of seeking their improvement.

Individual club members included: William Livingston, William Smith, James Duane, Samuel Jones, John Tabor Kempe, Peter Van Schaack, Rudolphus Ritzema, Benjamin Kissam, Gouverneur Morris, Stephen Delancey, John Jay, and others.

The decisions arrived at as a result of the debates acquired great authority, and were considered as settled by the New York bar generally.

Peter needed to search in the Council Books and Journals of the General Assembly in order to determine which Acts had received royal assent, which were repealed, and which remained probationary.

[11] In May 1775, Peter Van Schaack moved to Kinderhook in search of relief from the growing turmoil of New York City and out of concern for the health of his family.

[14] Van Schaack was committed to seeking a peaceful resolution to the hostilities, and he refused to take up arms because he feared the consequences for his countrymen.

[15] On 21 December 1776, the Committee for Detecting Conspiracies (created by the New York Convention) noted that Peter Van Schaack had “long maintained an equivocal Neutrality in the present Struggles” and “in General supposed unfriendly to the American Cause and from [his] influence [is] enabled to do it essential Injury.”[16] The Committee for Detecting Conspiracies summoned Peter Van Schaack and his brother to appear to ask whether they consider themselves to be subjects of New York or of Great Britain, and either impose an oath of allegiance or remove them to Boston.

The reason … it is premature, to tender an oath of allegiance before the government to which it imposes subjection, the time it is to take place of the present exceptionable one, and who are to be the rulers, as well as the mode of their appointment in future, are known….

"[18] In June 1778, Peter Van Schaack received permission from Governor Clinton to visit England to obtain medical attention for his failing eye sight.

“While in England,” Benjamin F. Butler wrote, “he was consulted in many cases involving intricate and important legal questions, and on one occasion in particular he was associated with Lord Chancellor Eldon, whose reputation, it is believed, was much enhanced by pursuing the advice and adopting the views of Mr. Van Schaack.”[21] He was often asked by his fellow countrymen to help them secure remuneration from the British government for the losses they suffered as a result of the revolution.

[23] He wrote that he initially believed that British actions towards the American colonies were motivated by a need for “solid revenue,” but that he came to realize that “the real design was to enhance the influence of the Crown, by multiplying officers dependent on it.

In short, to establish in the Colonies the system of corruption by which their government here is carried on.” Van Schaack came to believe that the British constitution, he had so admired, was no longer in existence.

[24] In 1784, an act was passed by the New York Legislature restoring Peter Van Schaack and three other men, "all their rights, privileges and immunities, as citizens" upon taking the oath of allegiance as prescribed by law.