Depends on your passport. If your on the list of visa not required or waver your ok.
An Indian for example wouldn't be able to and would be turned back at the border if they didn't have a visa. To be honest its Indians I have always had the problems with immigration with.
If said person was to arrive by GA and not declared or bypassed immigration controls, and then was found to be in the country the PIC would get done for transporting an illegal.