a valid "contract". He added that the state had no right to annul the purchase of the land since doing so would impair the obligations of the contract. The definition of a contract propounded by Chief Justice Marshall was not as simple as it may seem. In 1819, the Court considered whether a corporate charter could be construed as a contract. The case of Trustees of Dartmouth College v. Woodward involved Dartmouth College, which had been established under a Royal Charter granted by King George III. The Charter created a board of twelve trustees for the governance of the College. In 1815, however, New Hampshire passed a law increasing the board's membership to twenty-one with the aim that public control could be exercised over the College. The Court, including Marshall, ruled that New Hampshire could not amend the charter, which was ruled to be a contract since it conferred "vested rights" on the trustees. The Marshall Court determined another dispute in Sturges v. Crowninshield. The case involved a debt that was contracted in early 1811. Later in that year, the state of New York passed a bankruptcy law, under which the debt was later discharged. The Supreme Court ruled that a retroactively applied state bankruptcy law impaired the obligation to pay the debt, and therefore violated the Constitution. In Ogden v. Saunders (1827), however, the court decided that state bankruptcy laws could apply to debts contracted after the passage of the law. State legislation on the issue of bankruptcy and debtor relief has not been much of an issue since the adoption of a comprehensive federal bankruptcy law in 1898. Clause 2: Import-Export Clause Still more powers are prohibited of the states. States may not, without the consent of Congress, tax imports or exports except for the fulfillment of state inspection laws (which may be revised by Congress). The net revenue of the tax is paid not to the state, but to the federal Treasury. Clause 3: Compact Clause Under the Compact Clause, states may not, without the consent of Congress, keep troops or armies during times of peace, or enter into agreements with other states or with foreign governments. Furthermore, states may not engage in war unless invaded. States may, however, organize and arm a militia according to the discipline prescribed by Congress. The National Guard, whose members are also members of the militia as defined by , fulfill