Another variation I think I read about is where the law is implemented with an explicit goal that must be achieved by a certain date, and if the goal is achieved, the law becomes a regular law; if the pre-defined metric is not met by the certain date, the law disappears.
A law requires further legislative action for it to not disappear on a certain pre-set date.
https://en.wikipedia.org/wiki/Sunset_provision
Another variation I think I read about is where the law is implemented with an explicit goal that must be achieved by a certain date, and if the goal is achieved, the law becomes a regular law; if the pre-defined metric is not met by the certain date, the law disappears.