@ htark thanks for correcting me, you are rite! it does say on the cic website about 3 months, but i couldn't find a official reference about the one year validity.
http://www.cic.gc.ca/english/information/security/police-cert/intro.asp
Who needs a police certificate?
In general, you and all the people in your family who are 18 or older need to get a police certificate. You must get one from each country or territory where you have lived for six or more months in a row since the age of 18.
The certificate must be issued no more than three months before you apply.
If your certificate is in a language other than English or French, send it when you apply, along with the original copy of a translation done by a certifed translator.
