There are only three companies that are allowed to make case law search engines in Ontario and Google isn't one of them.
The decisions of Ontario courts are public information but there are only three organizations that you can get them from and none of them provide bulk access. That last part is the key because that's what a truly public system would have: the ability for anyone to access Ontario's cases and make use of them how they would like (e.g. building a better search engine).
You can read most Ontario cases for free by going to www.canlii.org. You can also buy an expensive subscription (Quicklaw or WestLaw) from one of two companies (Reed Elsevier or Thomson Reuters) to gain access to Ontario's decisions. What you can't do is make your own case law system/search engine because you can't get bulk access to cases.
Canlii is owned by the law societies of Canada (the lawyer regulators run by lawyers in each province). Canlii explicitly forbids indexing (that they haven't permitted) and bulk downloading of cases. Quicklaw and WestLaw similarly don't allow bulk access (e.g. Quicklaw terms 1(e)).
I inquired with the Judicial Library of Ontario about what the terms of the deals are with the three publishers and received this response:
“The courts comprise an independent branch of government and any agreement between the courts and the legal publishers that governs the publication of the courts’ judgments is permitted to remain between the parties. Each court distributes decisions in a manner that it deems to be appropriate. Decisions of the Court of Appeal for Ontario are published on the Ontario Courts website. Due to the very large number of judgments released by the Superior Court of Justice and the Ontario Court of Justice, those courts distribute their judgments exclusively through the legal publishers. These two courts maintain similar, but not identical, lists of publishers.”
In short: there's a secret deal and you don't get to know who the people are who get the cases, how much they pay or how to join the club. It also means that the only innovation allowed with respect to Ontario case law is that provided by the three companies that have access.
Google can't make a search engine for Ontario cases (like they did in the US). You can't either.