Supreme Court of Canada on restitution of invalid taxes

I've just caught up with the Supreme Court of Canada's decision in Kingstreet Investments Ltd. v. New Brunswick (Department of Finance) [2007] SCC 1 (11 January 2007) which decides:

• A remedy for payment of ultra vires taxes is available as of constitutional right, rather than under the law of unjust enrichment.
• The right to restitution is a matter of fundamental constitutional principle. "The
  action for recovery of taxes is firmly grounded, as a public law remedy in a
  constitutional principle stemming from democracy’s earliest attempts to circumscribe
  government’s power within the rule of law."
• The passing‑on defence is not available.
• The protest and compulsion doctrine is not applicable.
• Limitation periods may be valid.