What will happen?
Hello JoeF and other people in this forum,
The website you have mentioned provides the following information:
-------------------------------------------------------------------------
Once the DHS office in London receives your completed Form I-407 and the returned Permanent Resident Card, the appropriate documentation stamps will be placed on the form along with the DHS officer’s signature. A copy of this form will be returned to you. This is your receipt and validates the return of your Permanent Resident Card. You should keep a copy with your passport in the event you are queried about your prior U.S. immigration status.
-------------------------------------------------------------------------
What happens if you are not that honest, thus, if you do not return your Green Card? When you enter USA with your Green Card and officers at the PoE notice that your permanent place of living is not USA, but abroad.
Will you be arrested?
Or do you have to leave USA immediately with the next plane?
Will you be banned from entering USA for the rest of your life? Or for how much time will you be banned?
Do you get the chance to enter the US with your Green Card, hire a lawyer and then go to US court?
Are there any new laws in the post-9/11 time?
These questions might be very interesting for many users here in this forum. Otherwise they wouldn't be that much afraid of staying abroad for a certain time.
GreenGo