Lets pretend for just a moment, that magic is real. Now go into the local Magical library and you notice an interesting book called "How to Devour Souls for Idiots" and start to read. However as you read on you a look of horror grows on your face as the realize that this is a very bad thing to do to people so you immediately try to set it on fire only to see that its enchanted to keep people from hiding its knowledge from others. Sadly you have to leave it there where literaly any one can read it. The following week you hear on the magical television how a Magical preschooler was discovered dead next to that very same book after they accidentally summoned SATAN. Just replace the library with internet, the book with ISIS application forms, the Magical preschooler with Depressed preschooler, and SATAN with ALALALALALA... Not a pretty picture is it?
The First Amendment, freedom of speech, is one of our most important values in the United States. We need to preserve that right. However, there are obviously some exceptions that need to be made. This particular question is very difficult. On one hand, sharing information is not necessarily doing any harm. However, if the information is about a group like ISIS (or the KKK) that promotes violence against other groups, I think it could be reasonable to ban the spread of that information.
First of all... The link provided in the question describes an incident that happened in London, where there is no Bill of Rights. But if it were to happen in America, it is known as treason. ISIS has declared itself an enemy to several types of western culture, specifically the United States. And the United States reciprocates by seeing ISIS as an enemy as well. So, any attempt to intentionally and directly aid an enemy of the United States in it's destruction is treacherous, and the rights of traitors are not protected by the Constitution.
The Islamic State is culpable for a huge number of deaths in the Middle East. Recruiting for them should be an offence in any region of the world. There is no logic behind the actions of IS, only hate. I would argue that some of the same restrictions should be applied also to other modern terrorist organisations, like the KKK.
The Islamic State is evil and any propaganda they spread is evil too. Anyone spreading their ideology must be jailed so that he understands the consequences of his actions. Islamic State is a threat to the entire world and the right to information is not more important than the right to lead a safe life.
We have a right to speak about whatever we want to. So if I want to say how a terrible Governor like Rick Scott is, then I can. However if I want to talk about terrorist groups, I feel no one has the right to stop me from talking about it. I understand that people think its a touchy subject, regardless we still need to respect other peoples rights and let them hand out leaflet. Its not like they are active members are only doing it to recruit, then I don't see anything wrong.
Making the sharing of information illegal goes against citizens' 1st Amendment rights. This unjust law could cause many misunderstandings, as someone spreading information about the hate for a terrorist group could make them a hate group as well. Just because the viewpoint of America is against terrorist groups like ISIS, doesn't mean that all its citizens need to share the same opinion. As long as those who are giving out this information are not actively spouting treason about America, this should not be illegal.
This law is very vague, and could cause people to be wrongly jailed, fined, or executed. Though there may be some who hate ISIS more than others, that doesn't mean that people who may support some ideas of ISIS (other than against the US) have to give up their ideals for someone else.
The constitution protects freedom of speech and expression; ALL speech and expression with a few narrowly defined exceptions. We can't make it illegal to hold an unfavorable opinion. Unless something specific in the leaflets has been deemed illegal by the courts, simply disseminating information is a protected right. Putting someone in jail for expressing their beliefs or voicing an unpopular opinion is wrong.