OK, so imagine the situation...
You're sitting in the front row, outfield seats in Right Field. Bottom of the 7th, man on first, 2 outs.
Batter hits the ball, comes sailing right at you... you try to catch the ball, but it bounces out of your hands and back onto the field.
Now, this is important: You never got out of your seat, it happened so fast. So you are clearly behind the railing. Oh, and your seat is about 25 - 30 feet above the field.
So, is this hit:
(a) A Home Run, since it cleared the rail
(b) A Book Rule Double, since it appeared to the umpires to hit the rail (on the field side) and bounce back in
(c) Fan Interference
Initial ruling on the field... (b) Double. Runner scores from first since there are two outs, he's running on contact.
Home manager comes out, argues that it was a home run, requests video review. Umps confer, decide to review the video. Home TV viewers are shown multiple replays, clearly showing the fan's hands being hit, that he's not leaning over the rail & hasn't left his seat.
No brainer, right?
After a 4 minute review, the umpires rule: Fan Interference. Batter is credited with a Book Rule double, but the runner from 1st is NOT put back on base... if it's by rule, he can only advance 2 bases, not 3... and the run is left in place.
And the best part? Since it's ruled Fan Interference, ballpark security removes the fan from his seat and he's escorted out of the park.
Now, how's THAT for adding insult to injury?
(Incidentally, the player who got screwed out of his first HR of the season did score after a single by the next batter, and the home team rallyed from a 5 - 0 deficit going into the 7th to win 10 - 7.)