When a bill has received Royal Assent, it becomes an Act of Parliament and is assigned an act number for that year or session of Parliament - thus Sessional acts. This series of numbered acts includes both principal (original) and amending acts.
As this number is unique, it is a useful device for tracking a particular act, even if you dont have the title. These acts are available online and are also issued in pamphlet form on Royal Assent. At the end of each year they are reissued in numerical order in bound volumes.
The Cannabis Control Act 2003 (WA) is Act number 52 of 2003 - (original act)
The Energy Legislation Amendment Act 2003 (WA) is Act number 53 of 2003 (amending act)
Principal numbered acts are sometimes referred to as acts "As Made" because they are in the original version before any amendments have been incorporated. It is sometimes necessary to compare the online compilation act with its original "as made" version in order to ascertain the changes which have been made over time.
WA and CTH Numbered Acts are available on the shelf in the Legislation Collection on Level 2 of the Beasley Law Library.