Traditionalist..I'm sorry to hear about your friend, but Felix is right.

There are two main reasons why your friend may have got sent back:

1) If your friend had a criminal record, he would need to apply for a traveling visa within 12 months after serving the sentence. This can be done at the Japanese consulate. They would ask formality questions why you are going to Japan etc..They also need a letter (of proof) from your Japanese contact to ensure they will look after you while you are there etc.. If your friend failed to present this visa at arrival, they most certanly send him back.

2) Ticking yes while filling the arrival card than give wrong answer to the questions when got there. I don't know what happened to your friend exactly, but if he had something to drink on the plane and got intoxicated on the way there, he could have easily flunked like Felix said. Like I said, I don't know and your friend may not have had something to drink. (Just guessing)

If that system was not available, it will be very hard to do business travel and such to Japan. There are thousands of business people and people from other sports out there with criminal records who travel to Japan and other countries.

Like I said it's may appear unfair to your friend, but it also unfair to use Mark Hunt and Paul Kingi. They utilise the system just normal people who travel to Japan with past criminal record.

Beside, it's stupid not to no if you have a criminal record anyway. After Sept 11, they get more nervous and will go the extra mile to dig deep into your record. One of my guys tried that trick (not ticking yes) even before the Sept 11 and got sent back. This was just to Australia. I asked him prior to the travel and he assured me everything is fine...Well, he got send back from Sydney and learned from the experience.