The answer to the first question is, of course, yes: Generally speaking, anyone can be sued for anything in this great country of ours, no matter how lacking-in-merit the case might be. (Of course, if the case is truly frivolous, the courts may, in some instances, have the power to impose sanctions on the plaintiff or his attorney.)
The answer to the second question is not entirely clear, although the law is better for publishers (and perhaps also for authors) than one might guess.
There was, in fact, a case involving an encyclopedia of mushrooms. Some readers, relying on misinformation in the book, did collect and eat poisonous mushrooms, becoming so ill that they required liver transplants. Ultimately, in this important decision, the Ninth Circuit found that the publisher had no liability to its readers for the nearly-deadly information. Essentially, the court concluded that imposing liability on the publisher would open the door to the prospect of unlimited liability that could severely threaten the free flow of information. Here is how the court explained its reasoning:
Although there is always some appeal to the involuntary spreading of costs of injuries in any area, the costs in any comprehensive cost/benefit analysis would be quite different were strict liability concepts applied to words and ideas. We place a high priority on the unfettered exchange of ideas. We accept the risk that words and ideas have wings we cannot clip and which carry them we know not where. The threat of liability without fault (financial responsibility for our words and ideas in the absence of fault or a special undertaking or responsibility) could seriously inhibit those who wish to share thoughts and theories. As a New York court commented, with the specter of strict liability, "[w]ould any author wish to be exposed ... for writing on a topic which might result in physical injury? e.g. How to cut trees; How to keep bees?" . . . One might add: "Would anyone undertake to guide by ideas expressed in words either a discrete group, a nation, or humanity in general?"Similarly, the courts have found that a publisher was not liable for an injury to a student who was injured while performing a science experiment, following allegedly mistaken directions in a textbook. Decision here. Dow Jones had no liability to readers for publishing mistaken financial information. Decision here. A victim of sexual abuse could not recover from a publisher that allegedly misrepresented the qualifications of an attorney that she hired. Decision here. Planned Parenthood was not liable for the "wrongful conception" of a child based upon allegedly mistaken information in a contraception pamphlet. Decision here. See also this case in which a publisher was found not to be responsible for the death of a reader arising out of the publication of allegedly hazardous information in a diet book. And then there is this famous (to media lawyers) and bizarre case in which Hustler was found not to be responsible for the death of a teenager who allegedly imitated an autoerotic practice described in an article in the magazine. Decision here.
Many caveats are in order.
First, in a number of cases of this kind, the defendant was a publisher and not an individual author. Sometimes the publisher successfully invoked the argument that it could not be expected to fact check every instruction in every book it published. That same argument would not ordinarily be available to the author of an accused book. Accordingly, the author might face a greater legal risk than her publisher. See, for example, this case for personal injuries arising out of allegedly mistaken information concerning the making of tools, in which the claims against the publisher were dismissed, but the claims against the author went forward. See also Jones v. J.B. Lippincott, in which the court distinguished between the responsibility of the author and publisher of a textbook, which contained allegedly mistaken information that caused injury to a nursing student. The Lippincott court said:
Author liability for errors in the content of books, designs, or drawings is not firmly defined and will depend on the nature of the publication, on the intended audience, on causation in fact, and on the foreseeability of damage.Note, however, that the mushroom encyclopedia case, above, quotes with seeming approval language from an earlier case about protecting authors from unlimited liability, even though only the publisher seems to have been a defendant when the Ninth Circuit issued its decision. Moreover, in some of the financial information cases, the publisher also appears to have been the author of the "defective" information.
Second, some of the cases suggest that liability could be imposed if the publisher or author knew that the mistaken information was false, but went ahead and published it anyway.
Third, the courts have said that a different rule might apply in a circumstance where there was a special relationship between the writer or publisher and the reader that gives rise to a duty to speak with care. An example might be where you specifically contract to prepare a research report for a specific individual or company and it turns out that mistaken information in the report causes injury.
Fourth, and most fundamentally, no responsible author wants to cause injury to a reader, and there is no discounting the fact that publishing seriously mistaken information has a host of other detrimental consequences, ranging from damage to an author's reputation, to the cost of defending a lawsuit, even if the lawsuit is ultimately dismissed.
There is, in short, every reason for a writer to do his utmost to get his facts straight, to communicate instructions clearly, and to give ample warnings of the risks involved in a described procedure. That said, if the worst does happen, the law gives publishers -- and perhaps also writers -- some meaningful protections against open-ended liability to readers.
Postscript: Here are discussions of two recent cases in which readers have sought to impose liability on publishers and/or authors for perceived wrongs other than personal injury: the putative class action suit alleging that Jimmy Carter's book was falsely marketed as an accurate account of peace negotiations in the Middle East; and the case against James Fry and his publisher for allegedly misrepresenting a work of fiction as a memoir.