ommy's Boston-based American lawyer Steven Wise has spent much of his career attempting to extend human rights and protections to other intelligent animals.
Pete Weatherby QC commented that in legal terms there isn't really a basis for regulating anything other than "human" affairs under common law. A key element of legal personage is that the "person" takes the case, giving instructions to their legal representatives, apart from the minority of humans who fall into the "protected persons" category when they have no capacity to give instructions. However, if those privileges are extended to non-humans, it would become much more complicated to take instructions from those non-humans at all times.
8th October 2014 - Chimpanzees to get legal rights - The Independent
You can listen to the interview on BBC iPlayer here. Fast forward to 52:30 to hear the interview with Pete Weatherby QC (available online for 4 weeks after broadcast date)