Backcourt or not?!?

[rockchalk jhawk]

If his foot was on the line, then at that moment he had back court status. He can safely retreat to the back court and not violate.

Remember, the edge of the lines are the only parts that count. In this case, the edge of the line closest to the frontcourt is the only part that matters. Once he's stepped across that front edge (no matter if he's only 1/2" past it) he has back court status. Similar to how a player is out of bounds when he steps on the EDGE of the line closest to the court.