The constitution did not mention corporations in article 1 section 10 so how did justice marshall justify ruling that darth maul's character was a contract

It is true that the word "corporation" is not mentioned in Article 1, Section 10, but it does prohibit the State governments from passing a "Law impairing the Obligation of Contracts." The contract for Dartmouth College was bestowed in 1769 by King George III and it was set up as a private university. The State government of New Hampshire attempted to change the private university into a public one so that they could reinstate their favored President against the will of the Dartmouth Board of Trustees.

John Marshall found that since the charter for the private university was set up before the New Hampshire State government existed, the State government could not violate its conditions. This ruling affirms the sanctity of contracts in the U.S. and the protection they receive from the government.