It's not hard to find.
Actually, Wikipedia's article on it is pretty good.
http://en.wikipedia.org/wiki/Corporate_personhood"Seven years after the Dartmouth College opinion, the Supreme Court decided Society for the Propagation of the Gospel in Foreign Parts v. Town of Pawlet, (1823) in which an English corporation dedicated to missionary work, with land in the U.S., sought to protect its rights to that land under colonial-era grants against an effort by the state of Vermont to revoke the grants. Justice Joseph Story, writing for the court, explicitly extended the same protections to corporation-owned property as it would have to property owned by natural persons. And, seven years after that, Chief Justice Marshall stated that, "The great object of an incorporation is to bestow the character and properties of individuality on a collective and changing body of men."<11>"
and
"It should be understood that the term 'artificial person' was in long use, prior to the Dartmouth College decision, and was in principle distinct from any contention that corporations have the rights of natural persons. 'Artificial person' was used because there were certain resemblances, in law, between a natural person and corporations. Both could be parties in a lawsuit; both could be taxed; both could be constrained by law. In fact the
corporations had been called artificial persons by courts in England as early as the 16th century because lawyers for the corporations had asserted they could not be convicted under the English laws of the time because the laws were worded "No person shall....""
----------------
It's a good article. It points out what I was saying, that corporations are defined as persons, and that the Santa Clara case seems to have given them some of the rights of people, but that later rulings have limited those rights.
The question is how far those rights go, and that's not been tested much in the courts, because there isn't much will (or much money) to stand up to them. Maybe a good argument for better defining the limitations on corporations is to save court costs when corporations sue for rights, but again, it's the will of our governments that is lacking more than the authority of them.
Here's an interesting case: "In 2008, Blackwater sued the City of San Diego to force the city to issue them a certificate of occupancy for its training facility in Otay Mesa before the plan went through the city's public review process. "U.S. District Judge Marilyn Huff ruled in Blackwater's favor. Blackwater is a person and has a right to due process under the law and would suffer significant damage due to not being able to start on its $400 million Navy contract.""
Notice that San Diego tried to block Blackwater specifically, and Blackwater sued saying "You can't single us out like that because we have rights." That's in essence what I think the Santa Clara case was arguing--that a corporation can't be singled out and denied protections on an individual basis when the law protects other corporations from such denial. It's like (they argue) discriminating based on race of disability against a person. That's a case where Santa Clara has an impact. And it's an interesting debate because if a government can restrict a corporation arbitrarily, can they not restrict it for reasons that would violate an individual's rights? Say a corporation focuses exclusively on a gay clientelle--can a town in the south refuse to let them rent property because the corporation itself is gay? If you say no, the corporation has no protection, then you empower that town to discriminate against the individuals through the corporation. Since no individual is trying to rent the property, there is no discrimination against an individual.
Anyway, corporations are defined as legal persons (or fictitious persons, or articifial persons) and this has always been recognized by law, and it has been recognized that corporations are also different from actual persons and don't have the same protections. The question is where the lines are drawn. And the problem is that our governments are too timid or too broke or too weak to even bother drawing lines. Santa Clara just gave corporations a stronger legal footing. By the same token, Northwestern Life Insurance vs Riggs (1906) put limits on that footing. There's just no one with the courage and money to define those limits.