In Scotland, the type of behaviour you seem to be talking about would likely fall under a breach of the peace type thing … there are now a couple of variations of it, the common law one being the original … which is summarised pretty well below from a web page:
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Breach of the Peace
Source: Common law
Offence: When one or more persons conduct themselves in a riotous, or disorderly manner, anywhere, which alarms, annoys or disturbs the lieges (other people).
Arrest: Common law powers of arrest.
Notes:
This offence can take place anywhere i.e. a house, a public street or a private office.
Riotous: There is normally an element of noise, or ‘rowdiness’ or ‘brawling’ which is clearly causing concern to other members of the public e.g. swearing, challenging people to fight.
Disorderly: There is a more subtle element. The behaviour doesn’t have to be noisy but still of a nature that would cause concern to other people. Examples include: ‘Peeping Tom’ type behaviour, persistently following someone, delivering ‘threatening’ letters and ‘streaking’ or ‘mooning’.
To prove a Breach of the Peace the most important things to prove is that someone was Alarmed, Annoyed or Disturbed by the incident.
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So if being openly offended in public cause other people to be alarmed by it, then it would be an crime.
In terms of causing offence aspect, probably the first line that gets crossed with the lowest level of intent would be racial type comments. To be classed as a racial incident, if its perceived by anyone to be a racist comment, then its considered one.
Example:
A is talking to B and using free expression and words that neither A or B consider racist. C hears it, and C considers it to be racist. Even though C may have nothing to do with A and B’s discussion, its still considered a racial incident because of C.
You can see how that would be an easy line to cross.
