There is a limit to how far the state could or should reach into the private lives of its adult citizens.

Nevertheless, in the words of the charity Rape Crisis Scotland, the case of 31-year old John McDougall beggars belief. This man, jailed in 2000 for raping a 19-year-old girl at knifepoint while he was full of cheap booze, managed to contact 55 women on Facebook, using a false name, while behind bars and arranged to meet one of them after his release.

The Sheriff who returned him to custody to serve a further 34 months for breaching the terms of the Sex Offenders Register also expressed incredulity that a prisoner could set up a profile on a social networking site and use it to contact women. Inmates nearing the end of their incarceration need to be rehabilitated and cannot be expected to remain cut off from life outside but public safety must be paramount.

Social media sites claim to have attempted to safeguard users from sexual predators but filtering software used to identify and bar those on the Sex Offenders Register is useless when they can hide behind an alias, as McDougall did. He and others may take the view that they have done their time and are entitled to live a normal life but the prison service has a moral obligation to society and especially to survivors of sexual crimes to ensure that such offenders are closely monitored, so that they cannot put women at risk.

Since 2010 prisoners caught in possession of a mobile phone can have up to two years added to their sentence. It was recently reported that there have been 63 convictions for this offence since the law was introduced, suggesting that the rule is widely flouted.

A recent investigation found that some of Scotland's most dangerous criminals, including murderers, were using social networking sites to boast of their antics in jail and even post photographs. Clearly it is relatively easy to smuggle mobile phones and sim cards into prisons. If the management in Scotland's jails is not as rigorous in this activity as it should be for fear of a breakdown in law and order by cracking down on smartphones, that should be addressed. Have budget cuts limited the scope and number of searches?

Meanwhile, a generation happy to trust Facebook introductions should be on its guard. The internet is full of wolves in sheep's clothing.