SOurce: http://www.cic.gc.ca/english/information/security/police-cert/intro.asp#tphp idtphp
How to obtain a police certificate
Introduction
If you want to immigrate to Canada, you and your dependants may have to provide police certificates when you submit your application for permanent residence. Visa offices may also request certificates from students and temporary foreign workers.
What is a police certificate?
A police certificate is a copy of your criminal record or a declaration of the absence of any criminal record. Police certificates are different in each country and territory and may be called police clearance certificates, good conduct certificates, judicial record extracts, etc. They are issued by police authorities or government departments and used by Citizenship and Immigration Canada (CIC) to prevent individuals who pose a risk to Canada's security from entering the country.
Who needs a police certificate?
In general, you and everyone in your family who is 18 years of age or over need to obtain a police certificate. You must obtain a police certificate from each country or territory where you have lived for six consecutive months or longer since reaching the age of 18.
The certificate must have been issued no more than three months before you submit your application.
If the original certificate is neither in English nor in French, submit both the certificate and the original copy of a translation prepared by an accredited translator with your application.
How to obtain a police certificate
In most cases, it is your responsibility to contact the police or relevant authorities and request the certificate. When doing so, you may have to:
provide information or documentation such as photographs, fingerprints or your addresses and periods of residence in the country or territory; and
pay a fee for the service.
To find out if you need a police certificate from a country or territory in which you lived for six months or longer, consult the Procedures for Obtaining Police Certificates. You will find information on how and where to obtain police certificates, including police or government contact information. If this information is unavailable, contact the national police agency or the country's or territory's embassy or consulate.
If you have lived in a country that has changed its name or status, the police certificate should come from the current national authorities of that country as specified on our website. If you are unable to obtain a police certificate from a country because you are a refugee from that country or for any other reasons, please provide a written explanation.
CIC will also do background checks in all the countries or territories in which you and your family members have lived. These checks will determine if you have had any arrests or convictions, or if you are a security risk to Canada.
