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How to prove libel (from Wikipedia)
There are several ways a person must go about proving that libel has taken place. For example, in the United States, the person first must prove that the statement was false. Second, that person must prove that the statement caused harm. And, third, they must prove that the statement was made without adequate research into the truthfulness of the statement. These steps are for an ordinary citizen. In the case of a celebrity or public official trying to prove libel, they must prove the first three steps, and must (in the United States) prove the statement was made with the intent to do harm, or with reckless disregard for the truth.[17]
You can say whatever you want, pretty much, if you just preface with "IN MY OPINION" - opinion is exempted. And I would argue that a surgeon who advertises his services is a public figure, so he would have to prove actual malice in order to prevail in a libel suit.
But that doesn't address numbers 2 and 3 of your reasons. I just thought you might want to know that #1 is NOT a reason for not speaking up about ****ty treatment by your surgeon. Think of the other people you might be helping.
Why would anyone choose to have WLS IF they were capable of following those rules? Hell, I got my DS so I could be free of arbitrary, illogical "rules" about counting calories and forbidding myself certain foods.
Sheesh.