What's interesting to me is that in America, which does have pretty strong First Amendment protections, also has statutes for phone harassment:

http://www.firstamendmentcenter.org/telephone-harassment-sta...

> Telephone harassment is defined in many different ways. For example, while most states require some level of intent to harass or annoy, a few require only that the communication in fact harasses or that a reasonable person would expect it to harass...Telephone harassment often includes the following actions: calling repeatedly, anonymously or at inconvenient hours; causing the phone to ring continuously; using obscene language; or failing to hang up the phone. It can also include falsely stating that a family member of the recipient is injured or dead, or threatening to injure the recipient or a family member.

I support the non-guilty verdict here, but would someone be able to allege harassment over Twitter on the basis that it is similar to the statues on phone harassment (at least in America)? The argument is less about the content of the message and more about the annoying nature of repeated "notifications".