Canada's goal is to attract skilled workers who will become successfully established in Canada from an economic perspective.
To achieve this goal, Canadian Immigration authorities have designed a selection system based on the applicant's education, language skills, experience, age, arranged employment, and other adaptability factors that, in theory, demonstrates the applicant's likelihood of becoming economically established in Canada.
However, the Canadian government recognizes that the points awarded under the skilled worker selection system do not always accurately reflect an applicant's chances of successfully establishing themselves in Canada. As a result, Immigration, Refugees and Citizenship Canada (IRCC) Officers are authorized to use an alternate method of assessing an application. Under the concept of "substituted evaluation", a Visa Officer may make his or her own evaluation for the likelihood of the applicant becoming economically established in Canada. This method allows the Visa Officer to accept or refuse the applicant no matter how many points the applicant has achieved.
Note that "substituted evaluation" is not exactly the same concept as the consideration of "humanitarian and compassionate grounds" for approving an application. Under the concept of "humanitarian and compassionate grounds", the Minister of Immigration, Refugees and Citizenship in compelling circumstances, may grant a Canada Immigration Visa to anyone who is otherwise inadmissible. For example, if you believe that you would experience unusual and undeserved or disproportionate hardship if your application is not granted, you may be eligible to request consideration under "humanitarian and compassionate grounds."
Note: Since the move to the Express Entry selection system in January, 2015, there has been no vehicle for submitting a request for substituted evaluation, either in respect of an Express Entry profile or to overcome the eligibility criteria of the immigration programs now managed through the Express Entry system. Substitution of evaluation may only be considered in limited circumstances by an officer for applications made under Express Entry (i.e. a change in circumstance after an applicant has been deemed to meet the minimum requirements of the program to which they have been invited to apply).