Do Canadian lawyers take bribes to throw a case?
I know no lawyer should and most would not but within the context of
Canadian laws and Canadian lawyers' culture of ethics how common a
problem has bribery been?

In this question let us stipulate that bribery is either a monetary
payment or a promise of future considerations (the big account, the
big job offer)

Dunno about Canadian lawyers but Hartley Shawcross in his autobiog
tells of his problems as a young barrister on the UK circuit ... and
how he always lost to a combo of a certain judge and a certain
barrister.

There'a also a lot of anecdotal stuff elsewhere ...

Of course, the legal profession generally protects its own, although
the Serious Fraud Squad has successfully prosecuted some members of
the profession.