It is my understanding that the proposal in Canada was not actual
Shariah law but rather to provide a level of Shariah-based mediation in
family disputes. To actually allow Shariah law would require an act of
Parliment at least.

The rights of women in particular cannot be just waved away. If a
Muslim wife does not believe that she has the right to object to
spousal rape then all she has to do is not press charges. But if she
decides to press charges then obviously charges will pressed regardless
of what the Shariah might say.

In the United States, as I understand it and I am not a lawyer, the
children of a divorced couple are wards of the court. I feel sure that
this right of the children would not be casually brushed away even if
the parents were Muslims

And, of course, a Muslim husband might feel himself divorced after
three pronouncements but, of course, he would not be divorced under the
law. And so on.

Introducing Shariah law would be an immense undertaking. I believe you
will have trouble getting a rational response from the Muslim community
about this because the community doesn't really know what Shariah law
means any more than you or I do.

The correct response to a proposal for Shariah law is to ask the
advocate of the Shariah exactly what law code they have in mind and
insist on an accurate reference. It is a great conversation stopper.

If they actually name one ask them what it says about something modern.
Like speed limits. And if they can answer that ask them how this answer
came about. I think you can get the idea. Be polite but curious. Don't
worry about offending against Islam. Islam does not depend on the old
Shariah. A new Shariah that handles modern issues is possible. But so
far no such animal seems to exist.

Then, finally, there is the response that Shariah law is a Muslim
secret and none of the rest of us should be allowed to know about it. I
have posted an answer to this odd idea elsewhere..