Unlike (it seems) others, I see multiculturalism as a matter of individual freedom.
When Brad Jensen (in a DEOS discussion) says things like 'multiculturalism is treating people as a member of a group first' he is basing his precept on the idea that most cultures do, indeed, occur in groups.
It is this same sort of precept that leads someone like Clint Brooks to say that some aspects of culture must be over-ruled. These are precisely aspects where the norms of the group (say, to not speak freely) appear to over-ride the freedoms of the individual.
Except. That's not what multiculturalism is.
Multiculturalism is, at heart, the right of each person to choose to participate in a culture, where participating in a culture includes maintaining a language, following a religion, having certain values and beliefs, observing certain dress codes, and the like.
That this is a right is expressed by the consequence of a multiculturalist policy, specifically, that there shall be no reprisals or discrimination on the basis of their having made that choice, and that, all other things being equal, law and process will respect that culture (in other words, will respect the choices made by the individual).
In Canada, there was no specific opposition to the use of a specific cultural precept, including Sharia Law, to resolve civil and even minor criminal matters. Indeed, there is a lot of precedent for it. Canada employs both civil and common codes of justice. It also allows for First Nations healing circles. My own experience is that it also allows for various practices of mediation and arbitration.
Where objections tend to be raised is in the matter of whether a given individual has voluntarily chosen to be a member of a culture, and to be governed by such sanctions. This is particularly tricky in the case of minors, where such decisions are made by the parents. It is also tricky in cases of power imbalance, as for example a young woman under the control of her father and other males in the community.
But these concerns are not objections to multiculturalism. They are objections to coercion and abuse in the name of multiculturalism (or in the name of a particular culture). And these objections apply across cultures (and to a large degree are based on objections to the sanctioned mistreatment of women that appears in almost all cultures, including Christian, Muslim, Hindu and others).
This observed, there is utterly no contradiction between multiculturalism and freedom and democracy in a society.
Take the matter of free speech. I may belong to a culture that prohibits free speech. It may even require a vow of silence. If, however, I am free to walk out the front door and to cease being held by that vow, then my freedoms are not being infringed. It is only in the case of coercion that my freedoms are being infringed.
The law, properly so-called, in a multi-cultural environment, bedcomes therefore something other than an instrument of enforcing moral policy. It is not intended to ensure adherence to basic values that we all share. Because we don't share them, and because values are not a matter of law, they are a matter of choice.
The purpose of law is to ensure that the different cultures can co-exist in a mutually supportive environment. To ensure, at a minimum, they they don't kill each other, take each other as slaves, impose their own religions and values on each other, and the like. The law is, in this sense, a lot like the traffic code. It is a pragmatic system that people respect becvause they see it as the shortest and simplest means to allow the preservation and practice of their own culture.
When one thinks of it, there can be no other way. No nation, no matter how assimilated its population, can ever hope to produce a monoculture. This means that in any nation there will be cultural differences. A system of law based on a culture - a religious law, say - will effectively discriminate against that culture. Members of that culture then face two choices: oblivion or resistence. A not insignificant number can be counted on to choose resistence. Hence a system of law based on culture can be predicted reliably to be an eventual cause of conflict and civil strife.