Getting the calls right

[joemoore]

With the players legs apart, the ball is going to go through the legs, the player reacts and closes his legs like a hockey goalie and then bends his knees so that when the ball strikes his legs he traps the ball.

I used to coach soccer as well and the player was intentionally using a soccer trapping technique to stop the ball. I just assumed any intentional play with the knee or below was illegal.

Is catching/trapping with the lower legs legal?