Employee Vacation Benefits
In the absence of employment agreements that mandate to the contrary, employers do not have to provide employee vacation benefits. In other words, there are no Federal employment or labor laws that require it.
Nevertheless, many employers have voluntary provided employee vacation benefits, just as they traditionally have provided other benefits that are not required by agreement or law.
Employers have done so voluntary to attract and keep employees. However, because providing employee vacation benefits is voluntary, employers may impose limitations and other conditions that are not in violation of state laws.
For example, your employer likely has the right to make you postpone your scheduled vacation leave for justifiable business reasons.
On the other hand, to rightfully impose vacation benefit conditions and enforce them, employers typically must clearly document the conditions, such as in policy handbooks for employees. Employers typically must also make employees aware of such conditions in advance, as well as the consequences for violating them.
If you violate a clearly-documented employee vacation benefit policy, then your employer likely has the right to deprive you of some aspect of the benefit, such as pay for the vacation leave that you took without authorization. Your employer might even have the right to fire you for company policy violation.
However, if employers don't fairly and equally apply vacation policies to all employees working in the same groups, including discipline for violating the policies, then "cheated" employees might be entitled to file lawsuits.
Despite that providing it is initially voluntary, if employers allow vacation pay to accrue by policy or agreement, then state laws might require the employers to issue accrued vacation pay to employees who've earned it, immediately or soon after voluntary or involuntary employment termination.
Many states have such laws. The laws typically require employers to include accrued vacation pay in employees' final paychecks; but, even in states that don't have such laws, if employer policies "promise" accrued vacation pay, then the employers typically must make good on their promise or potentially suffer the legal consequences.
On the other hand, if employees do something wrong to invalidate the promise, such as by not giving the required resignation notice according to company policy, then employers are likely not obligated to issue accrued vacation pay if state laws don't prohibit them from withholding it.
Read About Employee Benefits for information regarding avenues of relief, should your employer deprive you of the vacation benefit or any other employee benefit to which you're rightfully entitled. Alternately or additionally, consult a lawyer.