The reasoning that lead to the creation of a law (the intent) is considered the spirit of the law in the United States of America, while the legal text or phrasing (the literal interpretation) is considered the letter of the law.
For example, in the U.S. in the 18th century, Federalists like John Adams favored a "spirit"-based interpretation of the Constitution, so that Congress could keep a lot of power as long as it matched the Founding Fathers' general principles. Democratic-Republicans like Thomas Jefferson, on the other hand, believed that the Constitution should be interpreted strictly, and that Congress could not have any powers that were not explicitly mentioned in the Constitution. Their approch defended the letter of the law.