Employment and Social Development Canada (ESDC) produces a document called a Labour Market Impact Assessment (LMIA) that evaluates the effects of hiring a foreign national in Canada. An employer may choose to hire a foreign national if the LMIA is positive, meaning that no Canadian citizen or permanent resident is available to fill the post. A negative LMIA suggests that a permanent resident or citizen of Canada should occupy the position.
A foreign national cannot apply for an LMIA. Rather, LMIAs are documents which must be applied for by a Canadian employer.