The writs against the officers, who range from police constables to superintendents involved in the day to day handling of the case, were lodged by lawyers representing Neville and Doreen Lawrence.
The officers, who were told about the claims last week, are being sued under Section 20 of the Race Relations Act, which refers to discrimination on grounds of race. The black teenager was stabbed in April 1993 by a gang in a racist attack, while he was at a bus stop in Eltham, south east London.
The Metropolitan Police's initial investigation was strongly criticised in an inquiry by Sir William Macpherson. His final report, which was made public in February, concluded: "The investigation was marred by a combination of professional incompetence, institutional racism and a failure of leadership by senior officers."
Duwayne Brooks, who was with Stephen when he died, issued writs against 15 police officers in August. The Lawrence family's intention to sue was revealed in February.
Glen Smyth, the chairman of the Metropolitan Police Federation, condemned the legal action, describing it as a "crusade for vengeance". He added: "At the end of the day, Stephen's killers are not among the 42 police officers being sued."
A Scotland Yard spokesperson said: "The MPS [Metropolitan Police Service] will bear the legal costs for all the officers to defend these actions, and meet any damages that may be awarded against them."Reuse content