The private security firm G4S has barely been out of the headlines this week, due to its chaotic handling of the Olympic security contract. It makes another appearance today – this time in relation to asylum seeker Jimmy Mubenga, who died after being restrained by G4S guards nearly two years ago.

Mubenga, a 46-year-old Angolan, was being deported on a British Airways flight from Heathrow in October 2010. The father of five was restrained by three G4S guards before losing consciousness. Eyewitnesses described him complaining that he could not breathe.

The three guards were arrested two days after the death, which was classified as “unexplained”. During a 17-month investigation, they have been bailed eight times. It was announced today that they will not face prosecution.

Explaining its decision, the CPS said that there was “insufficient evidence” to prove to a jury that:

. . . any potential breach of duty of care owed to Mr Mubenga was a ‘more than minimal’ cause of his death.

The statement added that conflicting eyewitness accounts made it difficult to prove specifically that Mubenga was held in a “severely splinted” position – bent over with his diaphragm restricted – for long enough for asphyxiation.

The decision appears to have come down to a technicality. The CPS decision says that it was advised that a “breach of duty” did occur but that it was impossible to prove Mubenga was “severely splinted”. For anyone who has ever worked with asylum seekers and seen the inhumane treatment they routinely receive at the hands of authorities, this decision will come as little surprise. The complaints process very rarely ends in favour of deportees or detainees.

While Mubenga’s death was an extreme example, abuses during deportation are commonplace. Medical Justice published a report in 2008 that outlined nearly 300 allegations of such assaults. These included 42 deportees who complained of having their breathing restricted, several instances of neck injuries from having their heads pushed forward between their knees, and a punctured lung. In this context, it was merely a matter of time before somebody died.

In the time since Mubenga’s death, there's been little evidence that the situation is improving. The contract for deportations was transferred from G4S to Reliance earlier this year but internal memos seen by the Guardian implied that little had changed. The documents referred to “loutish” and “aggressive” behaviour by staff and a culture of a lack of respect for women and ethnic minorities among some employees. In a damning conclusion, the memo said: “Is this a company where women, ethnic minorities and those of diverse religions feel comfortable? Evidence would suggest: no.” The Guardian also reported that since last May, there have been seven further incidents of alleged mistreatment of detainees.

Given that asylum seekers are frequently some of the most vulnerable people in the world, it should be a source of shame too many of them face such brutality at every step of the process in the UK. Sadly, that does not appear to be changing any time soon.