BCA rules say a ball must touch a rail after contact or it is a foul:
3.9 Standard Fouls
If the shooter commits a foul, play passes to his opponent. The cue ball is in hand, and the incoming player may place it anywhere on the playing surface. (See 1.5 Cue Ball in Hand.) The following are standard fouls at eight ball:
6.1 Cue Ball Scratch or off the Table
6.2 Wrong Ball First; The first ball contacted by the cue ball on each shot must belong to the shooter’s group, except when the table is open. (See 3.4 Open Table / Choosing Groups.)
6.3 No Rail after Contact
The shooter hit the 1 ball below and it rolled but stopped short of falling in the side pocket? The ball crossed the plane of the rail but since there is no rail there it didn't touch a rail. I say it is a foul, my friend said no.

3.9 Standard Fouls
If the shooter commits a foul, play passes to his opponent. The cue ball is in hand, and the incoming player may place it anywhere on the playing surface. (See 1.5 Cue Ball in Hand.) The following are standard fouls at eight ball:
6.1 Cue Ball Scratch or off the Table
6.2 Wrong Ball First; The first ball contacted by the cue ball on each shot must belong to the shooter’s group, except when the table is open. (See 3.4 Open Table / Choosing Groups.)
6.3 No Rail after Contact
The shooter hit the 1 ball below and it rolled but stopped short of falling in the side pocket? The ball crossed the plane of the rail but since there is no rail there it didn't touch a rail. I say it is a foul, my friend said no.
