I would argue that surveillance was always going to be justified by starting with `vulnerable` children because many people find it difficult to object to anything that might safeguard children.
But it has now moved on to vulnerable adults and everyone else. In fact, Snowden gave the game away and legislation has had to be put in place to catch up with what was already happening. Surveillance is not a byproduct; it is the principle aim of the legislation.
Here is Scotland`s Prevent strategy
"Prevent is a strand of CONTEST the UK Government’s counter-terrorism strategy. It is designed to tackle the problem of terrorism at its roots, thereby preventing people from supporting terrorism or becoming terrorists themselves..."
"A Prevent Concern: A concern that does not have to be proven beyond reasonable doubt. It should however be based on something that raises concern, which is assessed by using the professional judgement of health or social work staff..."
"In this document it is suggested that Health Boards review existing arrangements for protecting vulnerable adults and children as a starting point, and consider adapting them to effectively deliver Prevent objectives so that Prevent is mainstreamed and embedded into frontline healthcare services..."
"Healthcare professionals working in hospital settings, the community and primary care, are well placed to recognise individuals, whether patients, carers or staff, who may be vulnerable and therefore more susceptible to radicalisation by violent extremists or terrorists. People with mental health issues or learning disabilities may be more easily drawn into terrorism."
"At the same time it is recognised that `there is no single profile of a person who is likely to become involved in terrorist-related activity, or single indicator of when a person might move to support extremism..."
"In many respects the dynamics and approaches of Prevent, as reflected in this guidance, are consistent with those that are already being implemented by Health Boards in relation to identifying and protecting vulnerable children and adults from potential harm..."
Yes, all based on hunches, suspicions and gut feelings and plenty of information sharing across agencies.
"The Glasgow Airport bomb attack in 2007 was staged by two healthcare professionals. It became known that in planning this attack, NHS computers and NHS email accounts (nhs.net) were used to source violent extremist information and to communicate with each other when planning the incident."
See also http://alicemooreuk.blogspot.co.uk/2015/10/a-stasi-state.html