no they do not. not only is this not established in law (in fact, congress has made it harder for civil suits to be filed), they are almost never brought unless there has been a large drop in stock price (not for tepid or slower-than-desired growth), the ones that are brought are usually dismissed, and the ones that are not dismissed are almost universally settled.

take a look at, for instance, http://en.wikipedia.org/wiki/Business_judgment_rule

Perhaps, but it's still such a widely held belief among businesspeople and shareholders that it's probably not a battle that would be wise to pick (very often).