On the heels of Jack Clark's statements on a St. Louis radio program that Albert Pujols uses steroids (based, Clark said, on what Pujols' former trainer told him in 2000), Clark has been fired by the radio station and Pujols has announced his intent to sue Clark and the radio station for defamation. Pujols expressed his desire to "send a message that you cannot act in a reckless manner, like they have, and get away with it."
As I've written before, the threat of suit in the wake of cheating accusations is a two-edged sword. On one hand, the failure to sue often is taken as evidence that the allegations are true (i.e., "If the statements were false, why not sue?"). On the other hand, the threat of suit often looks like little more than posturing, an attempt to show that the accusations were false (i.e., "He wouldn't threaten to sue if the statements were true"), even if he has no real plan to go down this road.
Either way, there are reasons Pujols might not win his suit, even if Clark's statements were false. Pujols is a public figure and thus would have to prove by clear and convincing evidence that Clark spoke with "actual malice"--that he knew his statements were false or acted with reckless disregard for their false. Pujols' using "reckless" in his public statements is likely not accidental or coincidental. This barrier to recovery may deter him from initiating litigation in the first place. On the other hand, that legal standard may be exactly why Pujols would sue. Suing makes him look like a man fighting hard to vindicate his reputation against blatantly false and harmful statements, while the lawsuit's ultimate failure would have nothing to do with truth or falsity of the statements themselves.