First the disclaimer: I am not a lawyer
The question here is whether Bitcoin is subject to the Good and Services Tax (GST) in Canada. The GST is the Canadian version of a value added tax. The relevant legislation is the
Excise Tax Act http://laws-lois.justice.gc.ca/eng/acts/E-15/page-94.html#h-71. It may come down to whether Bitocin is considered "money" which is defined in the act as follows:
“money”
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“money” includes any currency, cheque, promissory note, letter of credit, draft, traveller’s cheque, bill of exchange, postal note, money order, postal remittance and other similar instrument, whether Canadian or foreign, but does not include currency the fair market value of which exceeds its stated value as legal tender in the country of issuance or currency that is supplied or held for its numismatic value;
There is probably a good case here under "and other similar instrument" for the position that Bitcoin is "money" and therefore not subject to the GST, given that its purpose is its use a medium of exchange in trade.