Work visa in the US

My freind is arriving in the US from Korea with a one-year work visa and an employer. What are his options as far as quitting that job at some point and moving to another town and getting another job? I think that the employer has paid for his visa, so I think there’s an ethical obligation to work for them at least for the summer season if nothing else. But after 6 months, could he move and work somewhere else? Also, what will he need to renew the visa at the end of the year–just show that he’s gainfully employed?

I’n not looking for the de jure so much as the de facto . I can get the former from the government, not the latter.

Unfortunately for your friend, the de jure basically is the de facto - work visa regulations are very stringently enforced in the States, and if he wants to change jobs he would be very very strongly advised to do it strictly by the book and to consult an immigration attorney if there is even the slightest irregularity with his situation.

Can’t really answer any other questions without knowing exactly which work visa he’s getting.

Our lab is transfering from Washington University in St. Louis to UCSF in San Francisco, and one of our co-workers is not allowed to join us because of her work visa. Lame lame lame, if you ask me.