After Rory Delap's debatable dismissal against Crawley Town in the FA Cup, the former Manchester United defender insisted the rules must be made clearer
Delap's red card was the first real flash point of the match, as he picked up his marching orders for a challenge on Crawley's David Hunt.
And Shawcross admits that players could do with some more information on the subject.
"I think we do [need clarification]," he told ESPN. "From what I've heard it wasn't that bad of a challenge, but I haven't seen it again so I can't really comment."
The centre-back was happy to have progressed through to the next round despite the disputed red card, and was adamant that the penalty which led to the opener was rightly awarded after Crawley's Kyle McFadzean was adjudged to have brought him down.
"It was a difficult one because we were down to 10 men," he continued.
"We were pleased to get the penalty and then the goal. In the second half we looked strong and then Peter [Crouch] popped up with the second goal and it was comfortable in the end.
"It was a penalty, so there was nothing to even up [after the red card]. I got in front to get the ball and then he swiped me down so it was a definite penalty."