In LA, the actor Robert Blake took his wife to dinner, but it didn’t end happily.

He was her tenth husband, she always married rich, older men, for money.

At the same time, she was having an affair with Marlon Brando’s son and she’d become pregnant.

She was shot dead in the car, Blake was arrested for murder, it seemed like an open-and-shut case.

Blake’s defence was that he had left his gun in the restaurant and when he went back to get it, a stranger must have come along and shot his wife.

The police had two witnesses who Blake had previously offered money to kill his wife: a stuntman called Gary McClarty, and another called Ronald Hambleton.

But members of the jury ignored them and kept requesting more forensic evidence.

“Had they checked the ballistics on the bullet?”

“Had they found any DNA anywhere, if not why not?”

They kept asking for irrelevant technical evidence and eventually found Blake innocent.

Attorney Steve Cooley called the jury “incredibly stupid”.

A year later in civil court, on the same evidence, Blake was found guilty of her wrongful death and fined $30 million. He appealed, but the verdict was upheld, proving he was guilty.

So what happened to the first jury, why did they get it so wrong?

It’s an example of what’s become known as “the CSI Effect”.

This is now a serious problem for the American system of jury trials.

CSI is short for “Crime Scene Investigation” a police procedural TV series, each week a murder is solved using state-of-the-art forensic techniques.

It quickly became the most watched show in the world with a weekly audience of 63 million.

It created spinoff series such as CSI New York, CSI Miami, and CSI Cyber.

Other shows copied it: NCIS, Criminal Minds, Law & Order, each with its own spinoffs.

Soon there was a glut of TV shows with murders solved by the same formula: 1) corpse discovered, 2) CSI investigates, 3) CSI interrogates, 4) CSI apprehends, 5) suspect confesses.

Every case is solved by hi-tech forensic evidence and, because it’s a TV show, it’s solved in 60 minutes: fingerprints, DNA, ballistics, appear in an instant on computer screens.

In real life, much of that isn’t possible and even if it were it would take weeks.

But the CSI Effect overrides common-sense, making it much harder to get a conviction without showing juries what they’ve learned to expect from TV shows.

444 prosecutors were interviewed, they said 56% of juries were influenced by the CSI Effect and they said 81% of judges were.

Which of course meant lawyers on both sides began to game the system: running many pointless forensic tests to make their case look impressive.

The CSI Effect is now a fact of life, it isn’t going away and it’s similar to what we do.

A belief in data, in technology, in whatever the latest fashion is.

Nothing wrong with all those things of course.

Relevant information is always helpful in making decisions.

But the key word is ‘relevant’.

More information, more technology, isn’t always better, it can be confusing.

Because it appears sophisticated it can cloud issues we’re supposed to be concentrating on.

The technology impresses us, even if it isn’t relevant.

That’s why, in the end, it needs to be someone with a brain who makes the final decision on what is and isn’t relevant.

When I would ask Mike Greenlees to make a choice between alternatives, he’d usually reply: “As well as, not instead of”.

Meaning one side doesn’t nullify the other, both are valid and we must choose.

Or to put it another way: technology as well as using our brain, not instead of using our brain.