Any free flight (btw "hang glider" refers to rigid wings and paragliders as well) pilot flying in class B, C, D and/or E airspace or applying for an Advanced rating must write the HAGAR examination. This is a Transport Canada requirement, hence the law. Anyone already in possession of a Canadian Pilot License already has access to Canadian airspace. A scan of the PL can be sent to the HPAC Office to fulfill the HAGAR requirement for the Advanced rating.
In order to write your HAGAR exam, Transport Canada requires you (the individual) to provide a Civil Aviation Medical Declaration (pdf) (advised to consult with your physician before filling it out) also found on the forms page and identification. This Medical Declaration does not expire by itself, as long as what is on it is valid. The exam is offered at Transport Canada Centres and Authorized Examination Invigilators. Check before to make sure and that you have all you need. You can ask your local school or hang gliding contact if they have information.
The HPAC / ACVL has developed a HAGAR Study Guide to assist pilots with the exam. Here is another HAGAR study manual developed in French by Bosco Daude. The HPAC study guide will be updated and another person will publish a study guide, in 2013.
The official HAGAR study guide from Transport Canada and all info related, is online:
TP 11408E Study and Reference Guide - Air Law and Procedures - Hang Glider
Transport Canada publish most study sources online. Here are the main two:
TP 14371 - Transport Canada Aeronautical Information Manual (TC AIM)
Canadian Aviation Regulations (CARs)
Transport Canada posts a few practice tests online, Test your knowledge!
Other related pages in Transport Canada: