The Crown Prosecution Service has issued final guidelines for prosecutors where cases involve communications sent via social media. These guidelines came into effect on 20 June 2013. 

The guidelines cover offences that involve both the sending and resending of communications via social media. It has been highlighted within the guidelines that the context in which the communications are sent will be highly material. The age and maturity of those who send the communications will also be considered.  

Communications capable of amounting to criminal offences: 

1. Credible threats of violence to the person or damage to property.

The threat must be credible and must create fear of apprehension in
those to whom it is communicated. Evidence of hostility and prejudice will
aggravate the offence.

2. Targeting an individual or individuals which may constitute     harassment of stalking.

Harassment can include repeated attempts to impose unwanted communications or contact upon an individual in a manner that could be expected to cause distress or fear in any reasonable person.

Stalking can include contacting, or attempting to contact, a person by any means.

The conduct in question must have occurred on at least two occasions and must form a sequence of events.

Communications sent on the basis of race, religion, disability and sexual orientation will aggravate the offence. 

3. Breach of a court order.

Court orders can apply to those communicating via social media in the same way as they apply to others. Therefore communications that breach court orders must be considered. Communications may have also breached other orders such as a Restraining Order or may have breached bail conditions. 

4. If the communications do not fall within these categories they must be considered separately; whether they are grossly offensive, indecent, obscene or false.

There must be an intention to cause distress or anxiety to the
recipient.

There is no legal requirement that the recipient must receive or see the
communication or is offended by it; only that the communication is sent,
delivered or transmitted. 

There are millions of communications sent via social media every month and so in order for the criminal law to step in, the communications must be grossly offensive. The test is "whether a message is couched in terms liable to cause gross offence to those to whom it relates." Communications that are in bad taste, controversial or unpopular is not enough.