From the Office of the Ombudsman (http://www.msu.edu/unit/ombud/excuses.html).

Class attendance at MSU is an "essential and intrinsic element of the educational process." The University attendance policy states that "no person is allowed to attend a class unless officially enrolled on a credit or non-credit basis with the appropriate fees paid. Students who attend, participate and strive to complete course requirements without formal enrollment will not receive credit for their work." (See "General Procedures and Regulations--Attendance" in the MSU Academic Programs catalog.)(.pdf)

As a result, a course attendance policy remains the prerogative of the instructor.  While it is the responsibility of students to attend classes, it is the responsibility of instructors to explain in the course syllabus exactly how the course attendance policy, if any, affects a student's final course grade.  This explanation should necessarily include the instructor's policy on excused absences and make-up assignments, quizzes, tests, exams, lab sessions and other course components missed during an excused absence.

MSU Example:
Students whose names do not appear on the official class list for this course may not attend this class. Students who fail to attend the first four class sessions or class by the fifth day of the semester, whichever occurs first, may be dropped from the course.