The actual text of the Constitution is the final and absolute yardstick all laws are measured against. When the Supreme Court considers the constitutionality of any law it must measure the law against the original text of the constitution and its plain meaning when it was written.
Notice of working hours/changes. Your employer must give you reasonable notice of any changes to your working hours, such as cancelling your shifts. They may request last minute changes (such as ringing you that morning to say that they do not require you to work) and you can choose to agree to this change.
Standard (40-Hour/5-Day Week) Work Schedules. On a holiday, part-time employees under standard work schedules are generally excused from duty for the number of basic (nonovertime) hours they are regularly scheduled to work on that day, not to exceed 8 hours.