A specialist firearms officer has wept at an Old Bailey court giving evidence about how officers on his team came to shoot dead Jean Charles de Menezes.
Mr de Menezes was mistaken for a suicide bomber
The officer, for the prosecution, said that "despite the outcome I was very proud of them", adding that they thought they were risking their lives.
The court also heard Mr de Menezes had cocaine traces in his body when he was shot in Stockwell Tube station in 2005.
The Met Police denies breaking health and safety laws over the incident.
It faces a single charge of exposing the public to risk.
Brazilian Mr de Menezes, 27, was shot seven times in the head on a train at Stockwell station on 22 July 2005, after being wrongly identified as one of the 21/7 would-be bombers.
Scotland Yard has been accused of making "fundamental failures" in the way it handled the operation.
The trial heard from Dr Kenneth Shorrock, who said Mr de Menezes had traces of cocaine in his urine and a breakdown product associated with cocaine in his bloodstream.
Dr Shorrock told the court he did not know how long after cocaine left the bloodstream it remained active in the brain.
Mr Menezes passed through the barriers followed by police officers
He said cocaine could cause anxiety and paranoia and make someone "abnormally fearful, abnormally apprehensive and abnormally suspicious".
But when questioned by Clare Montgomery QC, prosecuting, he said that if cocaine were in "active stimulant mode" it would be present in the bloodstream, which it was not in the case of Mr de Menezes.
The firearms officer, codenamed "Ralph", was the leader of the CO19 specialist firearms team that pursued Mr de Menezes after a "state red" alert to stop him was issued.
He said: "The only people running down stairs to confront the man that they believed to be Hussain Osman, a known suicide bomber, were police officers from CO19 and surveillance officers as well, while everyone else was running out.
"We were going forward to deal with this in order to protect the public, even though this man could have had a device on him."
Ronald Thwaites QC, defending, read from a statement made by the senior officer, in which he pointed out that police officers at the time believed they were risking their lives to protect the public.
The statement ended: "I hope that's not forgotten."
When Mr Thwaites asked him how he felt about being a prosecution witness, the officer, who was giving evidence behind a screen, became choked with emotion and was passed a box of tissues by the court usher.
Trial judge Mr Justice Henriques said: "I think the response speaks for itself."
'Not a normal operation'
The officer went on to describe the events immediately prior to the shooting of Mr de Menezes.
He said that the way the team was being run that day was "not the way we would normally operate".
This sentiment was echoed by another officer, codenamed Terry, who later told the court that officers had been told at a team briefing that day that "unusual tactics may be required".
Meanwhile, Ralph went on: "This was unique in the sense that we were being controlled from a distance in New Scotland Yard."
The judge asked: "You could see exactly where Mr de Menezes was and in the control room they didn't know what was going on?"
"Yes," Ralph replied.
The witness said that when the order to stop the Brazilian was given the object would have been to keep him alive.
His team would have been able to stop their target when he got off a bus and before he went into the Tube station, he said.
But the officers were still at "state green" at that time, and had not been placed on "state amber" by their controllers.
Police officers followed Mr Menezes down to the platform
Ralph said this meant that he, as the officer in charge on the ground, could not issue a "state red" alert authorising the stop.
Later, when the officer codenamed Terry gave evidence, he said a senior tactical firearms adviser had addressed a team briefing, saying that "unusual tactics may be required".
"His explanation was that any one of us may have to consider delivering an immediate incapacitating critical shot, in effect a shot to the rear of the head," he said.
Terry recalled being told "the individuals concerned were determined and well-prepared".