Guidelines for 'shaken baby' cases

The CPS also urged prosecutors to challenge defence experts who claim the three head injuries generally associated with the syndrome may be explained by a lack of oxygen, infection, or raised intracranial pressure.

The guidance updates that issued five years ago following concerns over the evidence of the paediatrician Prof Sir Roy Meadow in the Angela Cannings prosecution and other high profile cases.

The senior policy adviser in the CPS's strategy and policy directorate, Karen Squibb-Williams, said: "These are complex and sensitive cases.

"The guidance makes clear that it is unlikely that a charge for a homicide or attempted murder or assault offence could be justified where the only evidence available is the triad of injuries."

In cases where the three internal head injuries are found, "the prosecutor will always consider all the surrounding circumstances and the evidence in each case before reaching a decision", she said.

Ms Squibb-Williams added that prosecutors should strongly resist defence claims that the three specific injuries – bleeding into the linings of the eyes, bleeding beneath the dural membrane of the brain, and damage to the brain affecting function – may be explained by a lack of oxygen, infection, or raised intracranial pressure.

Ms Squibb-Williams added: "Each case will have its own individual facts and very careful consideration will be given in deciding whether there is sufficient evidence for a realistic prospect of conviction."