For example, two Spanish cartoonists were fined for depicting the Spanish king having sex with his wife captioned with the "unpopular opinion" that getting his wife pregnant was "the closest thing [the king has] done to work in [his] whole life": http://news.bbc.co.uk/2/hi/europe/7092866.stm
Here is the original cover: http://2.bp.blogspot.com/-mNFvFt4lGqU/U5JJpeCCkmI/AAAAAAAAF6...
My understanding is that the cartoonists filed an appeal, which was unsuccessful: http://www.20minutos.es/noticia/375143/0/ESPANA/ELJUEVES/
Citation? Is there actually a law that says this? Or is it hyperbole?
Even if all you've got are anecdotal court rulings, I would be interested in reading about it.
While legally not criminal, in practice you will find your right to free speech severely challenged.
I think all such "hate speech" laws are deliberately vague opinion policing and unrightfully limits freedom of speech. They all need to go.
I don't think anyone has been arrested for writing in 'unpopular opinion'. They've been arrested for writing highly racist content or directing abuse at others.