There is no evidence that a dolphin is a person. If fact one study declare that the larger brain matter was mostly insulation. From slashdot: http://science.slashdot.org/article.pl?sid=06/08/21/0358215

"While dolphins may have big brains, laboratory rats and goldfish can outwit them. It appears that the large brains are a function of their environment rather than intelligence. From the article: 'Dolphins have a superabundance of glia and very few neurons... The dolphin's brain is not made for information processing it is designed to counter the thermal challenges of being a mammal in water.' I guess this means that the Navy will start recruiting and training goldfish for those mine search and destroy missions."