Current legislation, enforced under The Children Act of 2004, says parents are allowed to smack their offspring without causing the "reddening of the skin".
Previously they could use "reasonable chastisement" with a judge deciding if they had over-stepped the mark. However, since the 2004 amendments the decision has been left to social workers.
Mr Lammy said a lot of parents in his constituency have been left confused by the changes and were reluctant to physically discipline their children in case they were contacted by social workers.
He added: "The law used to allow 'reasonable chastisement', but current legislation stops actions that lead to a reddening of the skin - which for a lot of my non-white residents isn't really an issue."
Non-white parents could get away with smacking their children more than parents of fair-skinned children, but they still do not. I think these parents scared of smacking their children must be SSMs.