Two groups were affected.
Some hacks were detained for 26 hours and six body searches before being sent home on a flight.
The problem related to press visas which US immigration officials claimed the journalists should have.
This is an "i" visa - it allows journalists from abroad to work in the US. But there's some debate whether such visas are actually required for short term visitors to conferences and the like.
The reason for the "i" visa category is to, quite naturally, protect journalists in the US from having their work taken by foreign journos.
It's questionable whether a visit to a US conference ever does that.
But the decision of individual immigration officers in the US is the one that counts.
In the past, some British journalists we know have been told they need an "i" visa on arriving in the USA and have had to pay $90 on the spot to be issued one.
You can find the report here. ยต
See Also
Two British journalists arrested at E3
INQUIRER hack caught in US Embassy Catch 22 situation