"This law is called the Broadcasting Act 1989 and it starts on 1 July 1989."
You can call this law the Broadcasting Act 1989. This law starts on 1 July 1989, except for some specific parts. Some parts, like Parts 3 and 4, sections 82 and 87, and Schedule 1, start when the law gets Royal assent, which is a formal approval, as seen in section 84(3) and other sections like Parts 3 and 4, sections 82 and 87, and Schedule 1.