Hearts boss Derek McInnes is furious at Celtic’s ‘disgusting’ penalty.

The law of handball is confusing at the best of times, but one factor always trumps all others.

If the arm is higher than shoulder height, the player is considered a high risk taker and there is a much greater chance of being penalized.

As Nicholson found out on Wednesday, if the VAR believes the ball touched his hand or arm at head height, it is likely to be awarded as a penalty kick.

Some might argue that the arm was only in this position because he was in a duel with Celtic player Auston Trusty, but that would carry little weight.

But there is one big problem.

Can we be sure it hit the arm at all? And if there was any doubt, how could it be such a clear and obvious error for VAR to ask the referee to award him a match-winning penalty kick?

The way the ball came back out of play during the throw-in suggested it hit Nicholson’s head, so the VAR must have thought it came out of his hand at the same time as well.

It seems exceptionally harsh to penalize this with a penalty because the ball touching the arm had no physical effect on where the ball ended up. This was all about the energy generated by the head.

The angles shown to referee John Beaton on the screen looked far from conclusive, but he needed just 20 seconds to make his decision. VAR Andrew Dallas must have spoken with great confidence.

But it leaves a bitter taste at a crucial moment in the title race.

Suddenly, things were in Celtic’s favor thanks to a questionable VAR intervention in stoppage time.