The segregation of football fans into home and away sections has been a part of professional football for so long that few can remember what it was like before it was put in place.
The controversy over last week's Europa League tie, where thousands of FC Köln fans acquired unwanted home tickets, has called into question the necessity of separating fans - a practice that is unique to football.
This week Graham, Terry and Jan analyse what happened at the Emirates and look at what - if anything - went wrong. Does segregation encourage bad behaviour or do home fans have a right to watch football without away fans sat next to them?
You can listen to the podcast here or if you right click on that link, you can download the MP3.