Stopping your notification that the service is not monitored can be forbidden by a strict enough secrecy order. It may be the least legally risky of the options. The fact that you will stop notification should be included in your terms of service.
All covered in my previous postings. This approach should be particularly applicable to ISPs as they generally have billing arrangement and can add this on as an extra service fee for each inquiry. Instead of court orders being a cost they become a revenue source.
steve
"The fetters imposed on liberty at home have ever been forged out of the weapons provided for defence against real, pretended, or imaginary dangers from abroad." --President James Madison (1751-1836)
