The six public interest factors against prosecution:

• The victim had reached a voluntary, clear, settled and informed decision to commit suicide.
• The suspect was wholly motivated by compassion.
• The actions of the suspect, although sufficient to come within the definition of the crime, were of only minor encouragement or assistance.
• The suspect had sought to dissuade the victim from taking the course of action which resulted in his or her suicide.
• The actions of the suspect may be characterised as reluctant encouragement or assistance in the face of a determined wish on the part of the victim to commit suicide.
• The suspect reported the victim’s suicide to the police and fully assisted them in their enquiries into the circumstances of the suicide or the attempt and his or her part in providing encouragement or assistance.
The CPS Policy for Prosecutors in respect of Cases of Encouraging or Assisting Suicide must be read alongside the Code for Crown Prosecutors and is effective immediately.

http://www.cps.gov.uk/news/press_releases/109_10/