Watford v Brentford

[RustyRef]

This is the image in its fullest.
I can see where they've drawn the line (on the defenders foot) but it just looks like the head/shoulder of the yellow attacker is ahead of it.
Don't see how they can be 100% certain and wish in these type of situations they go with on field decision.

View attachment 5603

Because the camera isn't in line, and as has been said that makes it impossible for the human eye to correctly judge. But the human eye can judge what part of the body is furthest forward, and technology does the rest. Completely agree that from this image it looks offside, but that doesn't necessarily mean it is and a still taken from in line would look different.

 

[ChasObserverRefDeveloper]

The hands and arms of all players, including the goalkeepers, are not considered. For the purposes of determining offside, the upper boundary of the arm is in line with the bottom of the armpit.

First page of law 11.

That's why I prefaced my first post with "Interesting one" - the defender's arm (including his shoulder) looked to be playing the attacker onside in the first picture, so very tight decision.

 

[ASM]

 

[ASM]