(CNN) -- As Michael Dunn, charged with murder in the killing of an unarmed black teenager, took the stand on Tuesday in his own defense, once again the nation focused on Florida, gun violence, and the evolution of self-defense. His testimony crystallized important points in this case. Dunn is not Zimmerman: We have to stop drawing comparisons between the Dunn case and that of George Zimmerman, accused of killing unarmed teenager Trayvon Martin. About the only thing in common between the two cases is that a human being lost his life, and another human being is the defendant. Oh, and John Guy, the prosecutor, who has had the roulette wheel of high-profile cases pick out his number twice in two years: He has been involved in both cases.
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Danny Cevallos: Michael Dunn's testimony highlights important legal points in his murder case
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Cevallos: Dunn is not George Zimmerman; his self-defense case is comparatively weak
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He says Dunn had to prove he had a reasonable fear of being seriously harmed
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Cevallos: Also, he had to explain why he fled, why he shot 10 rounds into the teens' car
If Dunn did a bad job of hiding his preparation, a jury might see through that, but that's on @placeholder -- not his lawyers.