See http://en.wikipedia.org/wiki/Fiduciary#Relationships
Under Corporation-Stockholders, Dodge v Ford is not cited.
There are actual corporate laws regarding shares and shareholders and corporate boards and whatnot, but they are mostly about trying to keep the game clean and not defrauding people, not "maximizing shareholder value."
Edit: So long as we're referencing wikipedia...
http://en.wikipedia.org/wiki/Dodge_v._Ford_Motor_Company
"Dodge is often misread or mistaught as setting a legal rule of shareholder wealth maximization. This was not and is not the law. Shareholder wealth maximization is a standard of conduct for officers and directors, not a legal mandate. "
It's actually a very interesting case, because the DODGE in Dodge vs. Ford is actually the guys behind the Dodge motors brand. They were using their investment in Ford motors to make money in order to start their own competing car company.
The notion that shareholders can bring about a suit in the United States because Google is not dodging enough taxes enough is absurd.