JonnyGutteridge
Newbie
Wisden explain it pretty well here...
Explained: Fingers Underneath Vs Complete Control - What The Laws Say About The Steve Smith Lord's Catch Debate
Steve Smith's tumbling grab to dismiss Joe Root in the Lord's Ashes Test has kicked up a controversy over whether the catch was a fair one or not.wisden.com
I understand the law but Smith didn’t have his fingers under it, or it wouldn’t have touched the ground as photographed. It was not a catch by any definition.