Scientists have read the minds of healthy volunteers using a brain scanner to detect what they were thinking. By placing the volunteers in the scanner after they had been shown three film clips, the researchers were able to tell which clip they were recalling.

The advance brings a step closer the prospect of a “thought machine” to detect what a person is thinking from their brain activity pattern. But the technique is still at an early stage of development and its capacity to discriminate between “thoughts” is limited.

Amid all the furor over the Bush administration’s warrantless wiretapping program a few years ago, a mini-revolt was brewing over another type of federal snooping that was getting no public attention at all. Federal prosecutors were seeking what seemed to be unusually sensitive records: internal data from telecommunications companies that showed the locations of their customers’ cell phones—sometimes in real time, sometimes after the fact.

According to the filings in Blake J Robbins v Lower Merion School District (PA) et al, the laptops issued to high-school students in the well-heeled Philly suburb have webcams that can be covertly activated by the schools’ administrators, who have used this facility to spy on students and even their families. The issue came to light when the Robbins’s child was disciplined for “improper behavior in his home” and the Vice Principal used a photo taken by the webcam as evidence. The suit is a class action, brought on behalf of all students issued with these machines.

The National Security Agency is facing renewed scrutiny over the extent of its domestic surveillance program, with critics in Congress saying its recent intercepts of the private telephone calls and e-mail messages of Americans are broader than previously acknowledged, current and former officials said.

The agency’s monitoring of domestic e-mail messages, in particular, has posed longstanding legal and logistical difficulties, the officials said.

Police are targeting thousands of political campaigners in surveillance operations and storing their details on a database for at least seven years, an investigation by the Guardian can reveal.

Photographs, names and video ­footage of people attending protests are ­routinely obtained by surveillance units and stored on an “intelligence system”. The ­Metropolitan police, which has ­pioneered surveillance at demonstrations and advises other forces on the tactic, stores details of protesters on Crimint, the general database used daily by all police staff to catalogue criminal intelligence. It lists campaigners by name, allowing police to search which demonstrations or political meetings individuals have attended.