(in some cases) preventing or mitigating death, injury or damage to a person’s physical or mental health.
If I was in Blighty this law would be causing serious damage to my mental health as I am sure it is doing to any number of people who really understand the potential for misuse/overreach. On those grounds alone it should be thrown out.
The chance of mass surveillance actually preventing any of this is miniscule. Surveillance like this can only be useful "After the fact" to show a pattern of behaviour. Good old fashioned police work is more likely to prevent incidents.