The Law Lords are to rule on an appeal by police killer Harry Roberts, who says secret evidence has been used to keep him in jail.

Roberts, 69, is serving life for the murder of three policemen in Shepherd's Bush, west London, in 1966, but his 30-year tariff expired nine years ago.
His lawyers challenged the appointment of a special advocate who has viewed secret evidence on Roberts' behalf.
The Parole Board has said sources would be at risk if it was handed over.