Comp time is NOT legal under federal law (FLSA) or Hawaii law for non-exempt employees

http://hawaii.gov/labor/wsd/ppt/TOP%20TE¦

all hours worked during the pay-period must be accurately tracked and paid for that pay-period,

all hours worked during the work-week must be accurately tracked and paid for in that work-week....

so it is perfectly legal for the employer to require you to work the weekend and they must pay you overtime IF you have overtime during that work-week.........

whether or not you are owed overtime can NOT be determined because you have NOT stated what days constitute the work-week for this employer....

the definition of a work-week is any 168 hour period (7days) as set by the employer......

the work-week must be fixed, it can NOT be changed without notice and it can not be changed to prevent the payment of overtime for time already worked.....

No -- if you are an hourly employee. Yes -- if you are a salary employee (exempt).

Are you an non-exempt employee? If so, you must be paid for that time.

Well you didn't mention two important facts: the state where you work and are you an hourly or salaried employee. You need to look at your state law more carefully because there is probably an exception for salaried employees. Salaried employees can be asked or expected to work more than 40 hours a week without additional pay. I'm not sure what you mean by your time being flexed. Are you going to get additional paid time off in the future? That's really the same as getting paid.

Non-exempt? No they can't legally.