It is interesting and bizarre to me how the foot-soldiers of the rightwing have continually railed against the so-called "nanny-state" and yet they are the first to call for state intervention when they find something that they don't like. They don't want the state to tell them that they can't, say, text and drive, or smoke in restaurants but they are more than eager for the state to come up with a dress-code. For me, this little act of cognitive dissonance is quite a feat and one that leaves me doubting the progress of social democracy.
The foundations of the modern freedoms associated with constitutional democracy are found in events like the French and American revolutions and the writings of people like Thomas Paine, Mary Wollstonecraft, and William Godwin. Though there are complicated theoretical and academic traditions associated with the questions of the limits of freedom, personal autonomy, and self-ownership, in public discourse we have used some pretty basic conceptual standards. We commonly legitimize individual freedom of action as long as it is doesn't "harm others." Though this is by no means a legal category, it is a kind of conceptual litmus test that people think about in relation to freedoms. For example, freedom of conscious, freedom to marry who we chose, freedom of movement, freedom of speech, freedom of expression, freedom of worship, these are the sorts of things that come to mind when we discuss a "free society" in private and public discourse, and they are the kinds of freedoms that are enshrined in various constitutional documents all over the world.
As long as your actions or thoughts aren't perceived as harmful or threatening to others, social democracy is generally thought to be tolerant of them. But how societies choose to limit freedoms is a complex issue. Perhaps the most famous example that is used in public discourse is the idea that your freedom of speech doesn't include yelling "fire" in a crowded theatre. This would be a so-called act of public mischief, because the impending stampede could cause harm to others, and limiting your freedom in this regard does nothing to substantially change your rights. Other limits to freedom of speech are more complex. For example many countries have decided to limit political advertising because even courts recognize the need for a more level electoral playing field. Your freedom of movement is limited to public spaces and doesn't include the private property of others or restricted government property, with the occasional exceptions of recognized easements.
There are other complex limits to your freedoms that are connected to perceived social goods. For example, the state compels you to wear a seatbelt or a motorcycle helmet because there are significant social costs associated with not doing so. Such freedom limitations are usually perceived as justified because they are relatively small and don't have huge impacts on people's lives and so are not perceived as too intrusive. But even here we grant exceptions in order to protect religious freedoms. In many places those who practice the Sikh religion are exempted from helmet laws so that they don't have to remove their turbans. The social "good" that this exception is meant to protect (the freedom of religion) is usually thought (at least by the courts) to outweigh the social risks associated with not wearing helmets.*
This brings us to the question of the niqab. Our question regarding freedoms should never, generally speaking, be 'how do I, as an individual, feel about someone's thought, conscience, actions or dress?" Rather, the question is "do those freedoms pose a significant impact or threat toward others or society?" If you want to limit people's freedom to marry who they want, for example, you can't simply appeal to a personal religious belief that gay marriage is some sort of unholy alliance. Since two gay people marrying each other has no direct impact on you as an individual, if you wanted to mount a meaningful argument against it you would have to contend that gay marriage is some sort of social threat, that is to say a threat to the stability or our society etc. However, the values of gay couples span the spectrum of our social values in general; some are conservative, some are liberal, some are atheist, some are religious, etc. In other words, gay couples are, in their beliefs, no different from straight couples. Thus, arguments that claim that we shouldn't legitimize gay couples because doing so poses some sort of threat to our social cohesion, seem to be extremely weak at best.
Arguments about the niqab are similar in nature. If someone choses to wear a niqab, other than potentially offending your personal sensibility, they don't have an individual impact on you. Thus, talk of banning a niqab (whether in citizenship ceremonies or in public in general) has to rely on some more abstract argument concerning what would have to constitute a public threat. This supposed public threat could be of two sorts; a perceived 'feminist' threat, or some kind of pseudo religious one. It is not uncommon to hear people say that the niqab is part of a system of gender oppression and therefore harmful to women. This may be true. However, going from this position to justifying a public ban on such clothing is a substantial and problematic conceptual leap. The danger involved here is, of course, one of extreme paternalism. By attempting to ban consenting adults from actions that they claim to be taking freely by their own volition, we are arguing at some level that these adults are unwittingly caught up in their own oppression. Such behavioural bans do, however, exist. Even consenting adults are not allowed to sell their organs or sell themselves into slavery. The reason that we as a society don't grant these rights is that we know that the most vulnerable among us would potentially fall victim to a system of exploitation. Tacit in the assumption of a niqab ban is a similar claim about exploitation. However, there are two important differences. One is that unlike a ban on selling yourself into slavery, say, a niqab ban involves a perceived religious practice. The other is that a ban on the niqab involves only one gender while other such bans refer themselves to the population at large. It isn't difficult to understand how potentially tricky it is to use a feminist argument to ban women from taking actions that they claim are not only religious but carefully considered and volitional.
An argued ban on the niqab that invokes a perceived cultural or religious threat is even more complicated. Whether we want to admit it or not, behind such arguments are centuries of prejudice, feelings that have resulted in countless acts of aggression and war by the West against muslim targets beginning with the Crusades. The concern here, though people often avoid its strict articulation for fear of sounding racists, are that Western nations are too tolerant, and that if we extend our religious rights too liberally we are opening the floodgates to some sort of Islamic take over of our society. I heard this argument regularly when I lived in the UK and I hear it here on AM talk radio. And politicians regularly stoke these fears with expressions like "jihadists" or the ever-popular "they hate our freedoms." The argument is problematic in a number of ways. Most importantly people commonly forget that many of the muslims that have arrived in Western nations over the past fifty or sixty years have been compelled to leave the Middle East because of wars, and in many cases these are wars that the West has helped to start and promote. Far from being a sign of some conspiracy to take over the West (as many unhinged rightwingers would have you believe) Islamic immigration to the West has often been a result of our own adventurism and militarism. Perhaps more glaringly obvious is the fact that muslims have chosen to live in countries like Canada when they could have in many cases chosen to live in non-Western states. Though their are crazy and aggressive individuals in all nations and religion, the bizarre notion of an Islamic conspiracy has no basis in fact and is simply a myth conveniently propagated by Western, mostly rightwing politicians eager to exploit fear as a way of winning votes. In fact, the opposite of this myth is actually more true, it is the Western nations that have continually been involved in cultural and military colonial efforts in Muslim nations not the other way around.
There is no question that politicians and rightwing pundits will continue to exploit fears and prejudices concerning such things as sexual preferences and religious beliefs in order to create social division and win support. There is also no question that many people will continue to misunderstand or misrepresent the principles of religious freedom and constitutional rights. The struggle for justice and democracy is, in part, the struggle against fear and bigotry; and a long struggle it is.
(*There are, of course, massive exceptions to all of these liberties which conflict with the principle of 'not harming others.' Perhaps the best example that I can think of is the use of carbon burning personal vehicles. The use of combustion engine automobiles does regular and widespread harm to others. But we accept this harm because the activity became a central part of our culture before we realized the dangers and thus we assume that, though a change must be made, it has to be made slowly.)