Prior to the Work Choices amendments coming into force, Certified Agreements; which are referred to as Collective Agreements in the amended Workplace Relations Act (CAs) and Individual Australian Workplace Agreements (AWAs) had to pass a No Disadvantage Test. This test compared a proposed agreement to an underpinning and relevant award that had or should have covered employees up until the proposal for an agreement. The No Disadvantage Test weighed the benefits of the award against the proposed agreement to ensure that, overall, employees were no worse off.
Hope this helps (it's from wikipedia btw)..
For a labour essay it would differ on the type of question, you have to be 'specific' cause there is lots of things to talk about generically.
But however things such as Fair work act 2009, workchoices 2006, Workplace relations act 1996 and trends would be fundamental to mention.