Back Court violation on a throw in

[Ref in PA]

Rule 9-9-2 applies to your situation, but has two exceptions. The first exception has to do with a jump ball and a throw-in. The second is a defensive steal. These exceptions basically say it doesn't matter where the player was when he jumped - ball possession was secured in the air and team possesion location is established when the player returns to the ground. There is a note for these exceptions and quoted here:

"NOTE: The exceptions allow a player to make a normal landing and it makes no difference whether the first foot down is in frontcourt or backcourt."

So, if you think the landing was normal - no violation; abnormal - violation. Isn't this easy?