Brain scans that test individual pain experience could be used to spot benefit cheats within 10 years, it has been claimed.
Imaging and other aspects of neuroscience could also be used in future to assess the public risk posed by convicted criminals, a report suggests.
But the Royal Society said any question of using brain test results as evidence in court should be approached with "great caution".
Brain Waves Module 4: Neuroscience and the Law was written by a group of experts in neuroscience, law, psychology, and ethics.
It concludes that brain scans cannot identify would-be murderers, and there is no gene that will inevitably turn a person into a violent psychopath.
However, the report does accept that neuroimaging and genetics may one day contribute to risk assessments in sentencing and probation decisions.
Working group chairman Professor Nicholas Mackintosh, from Cambridge University, said scientists were already close to being able to tell if a person is genuinely feeling pain or just pretending. Brain scans may soon reveal the neural pathways that provide a "signature" of subjective pain.
Such a test would open the door to identifying benefit cheats or fraudulent personal injury claims.
A team at Oxford University led by Professor Irene Tracey believes this could be achievable within 10 years.
Prof Mackintosh said: "She envisages that it will be possible to distinguish between someone who is genuinely in pain and someone who is malingering. It could provide evidence that tilts the balance of probability in such cases."
© 2011 Press Association