Justice Stevens' conclusion that the sovereign may interfere with First Amendment or other rights of privately founded and financed corporations because they are "artificial" creations is not only absent in the Trustees of Dartmouth College decision, but it is contradictory to it.
Founder and our fourth Chief Justice John Marshall wrote:
A corporation is an artificial being, invisible, intangible, and existing only in contemplation of law. Being a creature of law, it possesses only those properties which the charter of its creation confers upon it, either expressly, or as incidental to its very existence. These are such as are supposed best calculated to effect the object for which it was created. Among the most important are immortality, and, if the expression may be allowed, individuality; properties, by which a perpetual succession of many persons are considered the same, and may act as a single individual.
In other words, Justice Marshall's written opinion supports the principle that corporations may act and speak as any individual may, and the opinion notes that legislatures lack the power to take away "vested" rights.
The position that follows from Justice Stevens' must be that First Amendment rights are not vested. That is as dangerous a judicial notion as any I know.
Perhaps an even more radical and equally dangerous statement in the liberals' dissent is that "every corporate activity ... rest[s] entirely in a concession of the sovereign," and therefore could be "comprehensively regulated in the service of the public welfare." As I mentioned earlier, the opinion in Trustees of Dartmouth College makes the clear distinction between private corporations versus public (or civic) corporations such as cities and townships. Justice Stevens' language is pulled from the description of public corporations found in Trustees of Dartmouth College.
I do not know whether Justice Stevens' intent in failing to acknowledge this important distinction between private and public corporations was to influence more than just restrictions on First Amendment rights. The Marshall court makes clear, however, that government may not intrude on private corporations the way it may on public ones, and it must respect the private nature of private corporations even when their purposes may be for the public benefit.
That may be just horribly incompetent lawyering on Justice Stevens' part (although the other three liberal justices signed onto his dissenting opinion).