What are my rights if my employer is always weeks late in giving me my pay check?

If an employer pays his employees late--and that means either later than mandated by state law (many, but not all states, have laws setting timing and frequencey of pay) or later than the terms and conditions, even if oral or implied, not written, under which the staff works--the employer may be liable for his actions. For example, if paying employees late causes them to incur costs or damage (e.g. late fees, interest charges, etc.), the employer may be liable for those additional costs.

Of course, to recover your costs, you'd have to sue, which may not be worth it, economically; there are times when the other party is clearly in the wrong, but as a practical matter, there is little you can do about it, and this may be one of them. You may need instead to try to budget for late payments.

(Note: you could try contacting your state department of labor, especially if your state has laws about pay frequency and timing. They may take action for you. But given the many cases clamoring for their attention, including ones involving much more serious violations than paying late, they also may not take or get to your situation.)