Are my marriage documents still valid in Canada?
No. A marriage or marriage documents will be valid and recognized in Canada and for the purposes of immigration if it is legally recognized where it took place and under Canadian Federal Law.
It is important that when you submit your spousal sponsorship application, that you provide the necessary marriage documents to show that your marriage was legal in the country or state where your marriage took place.
Since your marriage will also need to be valid under Canadian law (federal and provincial), a marriage that was entered into by proxy will not be recognized and is considered invalid. Also, as Canada does not recognize polygamous marriages, they are excluded from the definition of marriage. Some countries have no divorce legislation or do not permit divorce; in this case, the responsibility is on the applicant to show that the applicant and their former spouse are separated and do not have a married relationship.