Compared to other political systems a working democracy is fairly robust. Sure the people may occasionally take to the streets, but the government is usually flexible enough to handle these problems. And this is because at some level a democracy is run by the people. But a democracy can only work if the voters are decent at making decisions regarding laws or about whom to represent them (otherwise the incompetence of voters will be magnified when they vote, and they will end up making choices that are worse than the choices that any one of them would make individually). Of course whether people can do these things well even at the best of times is a matter of debate. But anything that makes it harder for voters to make good decisions is harmful to democracy, and thus should logically be discouraged, probably by punishment. You see, in a system run by only a select group how the people as a whole view issues doesn’t matter for the health of the nation, only whether the leaders have the right perspective. But in a democracy widespread ignorance or misinformation can bring the whole system to its knees.
Thus in a democracy it should be a crime to misinform people, which we can define as telling people that something is true, with the intent to persuade them of that fact, when evidence to back up that claim is scarce or questionable. Why should misinforming people in general be a crime? Well, all kinds of facts are relevant to voting for laws or voting for representatives. For example, it is apparent we have a problem with global warming that we need to address. But if people are misinformed about global warming they may deny that it exists or deny that we can do anything about it. And both of those courses of action may have repercussions, namely the climate becoming more and more unstable until eventually someone is forced to do something about it, perhaps non-democratically. But global warming is just the hot topic of the moment. Who knows what may be relevant in the years to come, and thus any misinformation could be potentially dangerous to democracy as a whole.
Political advertisements are also harmful to democracy, perhaps as much as or more than misinformation. People can be manipulated by ads, and thus advertisements can sway a significant fraction of voters into making a decision that is motivated at least partly by them, which means that their decision is not being made completely rationally, which is bad for democracy. Ads also make it harder for poorer candidates to compete in general, which in turn means that the wealthy will always be overrepresented in government, and what is good for the wealthy isn’t always good for society as a whole.
But really making these things crimes would infringe on the freedom of speech. So we have to ask ourselves which is more important. Obviously making either spreading misinformation or political advertisements illegal has the potential for abuse. If the government was allowed to decide what was and what wasn’t misinformation then it is likely that it would simply try to label anything it didn’t like as misinformation. And if political advertisements were banned then the party in power would probably create public service announcements subtly in their favor, which would give them an advantage. But both of these problems can be overcome simply by giving the power to regulate these matters to some other body. Obviously the government can’t be trusted to regulate these kinds of things, for the same reasons that it has trouble passing and enforcing anti-corruption laws. But that doesn’t mean that nobody could regulate them fairly.
A more important question to consider is whether the right to free speech is simply more fundamentally important, such that it can’t be infringed even for other gains. The answer to that question depends on how you approach the nature of rights. If you approach them as basic ethical facts from which to work from then obviously they can’t be infringed, and the question is moot. I, however, think that rights are justified because they are good for society. Free speech is good for society because it allows people to openly debate issues share knowledge, which benefits everyone. In my opinion making spreading misinformation and political advertisements illegal would not negate these benefits, assuming that the enforcement of the laws was done with care. Making spreading misinformation illegal doesn’t prevent you from taking whatever stance you like on issues. You could still believe in psychic powers, and tell people that you thought that psychic powers existed. You just couldn’t tell people that there was good evidence backing up your claims. Similarly banning political advertisements wouldn’t prevent candidates from telling people what they stood for on various issues, and they should be elected instead of their opponents, they would just have to make the information available (say on the internet) and let people go to it, not spoon feed it to people.
Will these ever actually be made crimes? No. Too many people benefit from the way things are, and even if everyone wanted to make them illegal we would probably have to amend the constitution, which is not an easy task. I don’t bring these things up as a call to action, I simply wish to point out that democracy needs well-informed voters if it is to work. And to have well informed voters means that certain rights might have to be restricted. So what is more important, your rights or democracy?