If you want to sure you would have a much easier time suing Samsung for libel. A consulting firm they hired called Ad Metrix came out today with the dubious claim that Apple's latest commercial was their least effective yet. A few months ago a company called Added Value claimed that Apple's brand was less inspiring. Added Value is owned by WPP, one of Samsung's ad agencies. A while before that an outfit called Buzz Marketing announced that youth no longer thought Apple was cool and preferred the Microsoft Surface and Galaxy phones.
Much of the negative stories about Apple over the past several months can be easily tracked back to Samsung. If you want to sue someone then Samsung should be your target.