In general, if a foreign national wishes to work in Canada, they must first complete a Labour Market Impact Assessment (LMIA).
The LMIA requirement can be waived in some cases if the person seeking entrance to work in Canada provides a significant advantage.

When choosing whether or not to accept foreign employees into Canada, Canadian government officials must examine the effects on Canadian workers.
As a result, a labour market evaluation, referred to as a Labour Market Impact Assessment (LMIA), is usually necessary. However, under a significant benefit’ exemption, the LMIA requirement can be removed. The underlying premise is that in such instances, the good impacts of obtaining a work permit would outweigh the potential negative implications of failing to follow the usual procedure.

These are situations in which an LMIA is often necessary, but practical constraints prohibit this from happening if Canada is to gain, typically due to the lengthy processing timeframes involved with most LMIAs. Other considerations that are normally examined when evaluating a work permit application might mitigate in favour of the work permit being granted in such instances, aside from the lack of LMIA. The possible impact on Canadian investment and the economy, as well as the disruption of the Canadian labour market and the demands of the Canadian consumer, are all aspects to consider.