It seems that we've come full circle: last year, a bit of litigation seeking to have a chimpanzee declared eligible for all human rights in Vermont was shot down, but a similar case involving an orangutan in Brazil met with success. And as it happens animals have a long history of involvement in litigation.
All over Europe, throughout the middle-ages and right on into the 19th century, animals were, as it turns out, tried for human crimes. Dogs, pigs, cows, rats and even flies and caterpillars were arraigned in court on charges ranging from murder to obscenity. The trials were conducted with full ceremony: evidence was heard on both sides, witnesses were called, and in many cases the accused animal was granted a form of legal aid — a lawyer being appointed at the tax-payer’s expense to conduct the animal’s defence.
At one point, a group of rats were to be brought to trial for the crime of despoiling barley, but their barrister won them a dismissal over the objections of others who wanted them arrested for failure to appear in response to a summons. The barrister's argument appealed to judiciary's sense of justice: since the rats moved frequently, they may have been unaware of the summons, and even had they been, they were probably too frightened to obey, since as everyone knew they were in danger of being set on by their mortal enemies the cats.
The magistrate, unable to convince the villagers to keep their cats indoors for the duration of the trial, ordered the charges dropped.
In 1750 a man and a she-ass were taken together in an act of buggery. The prosecution asked for the death sentence for both of them. After due process of law the man was sentenced, but the animal was let off on the ground that she was the victim of violence and had not participated in her master’s crime of her own free-will. The local priest gave evidence that he had known the said she-ass for four years, that she had always shown herself to be virtuous and well-behaved, that she had never given occasion of scandal to anyone, and that therefore he was “willing to bear witness that she is in word and deed and in all her habits of life a most honest creature.”
These and other examples of jurisprudence may seem quaint, if odd, and people may attribute such cases to general ignorance that prevailed in the times. Yet this is precisely what animal-rights activists are seeking today. They believe that all animals are entitled to the same rights as humans - but with a difference: they don't believe that animals should be held accountable for their actions, which is what jurisprudence attempted to do in the 18th and early 19th centuries.