Your academic department will probably specify a referencing style for you to use. Consult the Cambridge Reference Management LibGuide for assistance.
If you are writing for publication, the editor will specify the style you need to use, and it may be detailed on the publisher or journal website.
Below is a list of links to the main referencing style guides.
To find out more about the University of Cambridge's view on plagiarism and good academic practice, as well as further advice on how and when to reference, visit these guidance pages.
OSCOLA - Oxford Standard for Citation of Legal Authorities
As official publications are often cited by lawyers, OSCOLA, is the style that deals with the topic most comprehensively. It is also freely available.
This House of Commons information factsheet has some information (page 5) on how to cite Hansard and committee debates.