Well, that depends on what you mean by "dock your pay" because you've said one thing but asked about another. Allow me to explain.
An employer is not legally required to provide leave, vacation, sick leave, PTO or any other sort of paid time off, in that sense.
So, an employer is allowed to set those rules concerning the use of their leave that they wish, including using it to cover your time off when you miss.
That's half the equation. The other half is that the Fair Labor Standards Act doesn't discuss leave when it talks about salaried employees and deductions. It only concerns your pay check itself and whether or not you get paid fewer hours on that paycheck.
So, if your employer uses two hours of leave to cover the two hours you missed (as an example), your check is the same as it would have been without the deduction....so, the bot***** *****ne is the same. That is ALL the FLSA cares about, so in that way it is legal.
If you were to run out of leave though, and missed two hours in a week (and it was for personal reasons...not FMLA leave related, because that statute actually allows hourly deductions for salaried workers) the employer THEN couldn't deduct from you because it'd make your paycheck actually smaller and that is the legal issue under the FLSA.
So, that's the analysis here under the law. When you asked if they can dock your pay, then the answer is no...they can't dock your pay. However, if you are asking if they can dock your leave, that's an entirely different legal consideration and the answer to that is "yes they can do so." And, they can do so without giving you additional compensation for working more than 80 hours.