Once when Stephen's father, Neville, broke down in tears as he heard in a court room how his son died violently and pointlessly at the hands of a racist mob.
The second when Stephen's mother, Doreen, allowed herself a celebratory "yes" as two men suspected of the killing were sent for trial. Getting the case to the Old Bailey was a milestone in the family's search for justice. And the third came as the Old Bailey trial started to crumble. Mrs Lawrence collapsed in tears.
Otherwise through their three year - and subsequently vain - struggle to find their son's killers, through frustrations at police progress, anger at the dropping of the case by the Crown Prosecution Service and dismay as they felt they became a pawn between competing anti-racist groups, they have maintained a dignified reserve. In the words of Mr Justice Curtis after the trial collapsed, "in the interests of justice" the Lawrences had remained "statesmanlike" throughout.
Stephen would have been 21 this year - well on the way towards his chosen career as an architect. A bright student he had been due to sit A-levels in English, design and technology and physics - and was expected to sail through them.
Instead aged 18 he happened to be waiting for a bus with a friend when a gang of racist thugs was on the streets - and he was killed. Murdered because he was black. He was the third black victim of racist killings in the area. For his parents, the only solace on which they could seize was the evidence of a couple, leaving church, who had gone to comfort Stephen. Louise Taff, said "he seemed very peaceful".
His friend Duwayne, who had yelled at Stephen to run and ran himself, was only able to give police the barest of details. Nevertheless, the hunt for the killers appeared initially hopeful. The names of various youths were given to police and the Lawrence family. Weeks later Duwayne Brooks picked outNeil Acourt and Luke Knight at identity parades. Both were charged with Stephen's murder.
But the following July the Lawrences suffered their first major blow - the Crown Prosecution Service dropped the charges for lack of evidence.
The decision prompted outrage in the black community and raised allegations that the case had been mishandled. It was later claimed that police failed to move swiftly enough, - losing potentially vital forensic evidence.
Stephen's family started their own inquiries. Then after the first anniversary of his death, the family had a meeting with Sir Paul Condon, the Metropolitan Police Commissioner, who initiated a second investigation. This inquiry, said the Lawrences, was faultless - it was just a year too late.
More evidence was unearthed, but nothing which would persuade the CPS to launch a prosecution - so the family, with the help of the police, launched a private prosecution - one of only four in 130 years of British legal history. Donations flooded in and lawyers offered to help for free.
Three men were finally committed for trial for Stephen's murder - Luke Knight, Neil Acourt and Gary Dobson.
Three years to the day after Stephen's death, the case came to trial only to collapse. The crucial identification evidence of Stephen's friend, Duwayne Brooks, was ruled inadmissible.
Mr Justice Curtis ruled the identification "contradictory and contaminated' and said it could lead to injustice. The family accepted it was neither "fair or proper" to try and put other material before a jury.