You're quite right, I DON'T have any evidence to show it was legal. I was simply trying to give Maggin the benefit of the doubt, that's all.
Another possibility that I just thought of - perhaps Supes didn't haul him away because he knew the charges wouldn't stick. I mean, there has always been a fair amount of prejudice against migratory workers, and if Harley's their boss, he may be a fairly powerful man in the community - perhaps by 'I know my rights', he's basically saying 'don't waste your time trying to put me in jail - I'll be out in five minutes'.