Nicky Jacobs, 45, has lived with a shadow cast over his life ever since the mob attack on PC Blakelock in Tottenham, north London, in October 1985, his lawyer told jurors at the Old Bailey.
Courtenay Griffiths QC launched an attack on the police and the Crown Prosecution Service for pursuing Jacobs so many years later, saying it was a "bleak and dismal story".
He said: "In my mind, the investigation in 1985-86 had more in common with the witch hunt of the 17th century than an orthodox attempt to solve a murder.
"It was flawed from the outset. The community that was already alienated from the law enforcement agency saw not bridges being built but a yawning abyss.
"If the evidence really suggested this man, Nicky Jacobs, has a case to answer, I have to repeat the question - Why has it taken so long to bring it?"
The trial continues.