29 CFR § 785.27 - General.
Attendance at lectures, meetings, training programs and similar activities need not be counted as working time if the following four criteria are met:
(a) Attendance is outside of the employee's regular working hours;
(b) Attendance is in fact voluntary;
(c) The course, lecture, or meeting is not directly related to the employee's job; and
(d) The employee does not perform any productive work during such attendance.