The economic concept of freedom of contract is directly related to religious liberties because those liberties include choosing methods of worship, professor Richard Epstein, of the University of Chicago Law School, said Thursday.

Epstein spoke to Utah State University students on campus as part of the Joseph M. Tanner Lecture Series on the U.S. Constitution.Freedom of contract involves the freedom of businessmen to choose who their trading partners will be and the way they will trade, Epstein said.

A businessman has a guaranteed right not to do business with those he chooses not to, he said. Also, it is a person's right to worship where and with whom he chooses.

The two clauses setting forth religious liberty in the Constitution are the free exercise clause and the establishment clause.

"The free exercise clause is short but important," Epstein said. "It says Congress shall pass no law against the exercise of religion."

The establishment clause says Congress cannot establish a national religion or favor one religion above another, Epstein said. This clause often causes problems with religious liberty.

"Did it (the establishment clause) mean not to favor one religion or to favor all non-religious activities?" Epstein said.

The clause brings up the question of funding religious groups as well, he said. "Is it possible to support all religions by public funds?" he said.

Epstein gave the example of Sunday closing laws many states passed and then repealed to reinforce difficulties with the establishment clause.

"Businesses were required to close on the Christian Sabbath. This was challenged by others who observed their Sabbath on Saturday."

Epstein compared other economic burdens and regulations placed on business owners to the additional Sunday requirement. "You'd probably admit that those other burdens are OK. Why isn't this one?"

This case was a clear establishment clause violation, he said.

Another conflict causing debate is whether states can make religious schools meet such requirements as teaching certificates, space and library sizes, he said.