Four people died and 102 were injured when the King's Cross to Leeds train came off the tracks at 115mph on October 17 2000.
The defence argued it was unfair to make the five rail executives scapegoats.
They worked in an under-funded industry which had been neglected by governments for more than 40 years, Jonathan Goldberg QC, defending one of the men, has told the court.
The five rail chiefs and Network Rail, formerly Railtrack, deny health and safety charges.
The individual defendants accused are: Balfour Beatty Rail
Maintenance Limited regional director Anthony Walker, 48; Nicholas Jeffries, 50, civil engineer for the same firm; Railtrack North Eastern managers Alistair Cook, 52, and Sean Fugill, 52, and Railtrack LNE track engineer Keith Lea, 55.
Engineering giant Balfour Beatty admitted earlier that it breached safety standards before the disaster. But the company did not accept all that the prosecution alleged against them.
The company has been formally cleared by Mr Justice Mackay of a corporate manslaughter charge. The judge has also cleared the five rail bosses of unlawfully killing the four who died.