If you are issued an ATP through an air carrier program with the VMC circle to land restriction, you are limited to 1000/3. You will find this within one of your regulatory (FAA approved) manuals. You will see no lower than published MDA or 1000ft and 3 miles above airport elevation to derive legal mins. If you are issued an unrestricted type without the circling you will see the verbiage to only be mins for your approach category of aircraft.