Libel statements imply false statements that are damaging to a reputation. Apple accusing Samsung of copying (in Apple's position) is a true statement, albeit damaging. If the court sides with Apple, then they aren't guilty of libel. If they don't side with Apple, they are are guilty of libel. The onus is on Apple to prove that they made a true statement (since Samsung has and will continue to hold the position that they did not copy).
I wouldn't have thought that accusing another company as copying would be a tough case to prove, but dang was I wrong.
Example of a bad case:
Person A goes to press and calls Person B "a ****"
The case goes to court. Person B demands the court to define what it means to "be a ****" and goes on to show that there is no real "number" to warrant the label. Person A can only present evidence of "multiple relations" but cannot counter the fact that being "a ****" has no real measure. Person A loses.
Example of a solid case:
Person A goes to press and calls Person B "a liar"
The case goes to court. Person A shows that Person B said X when in fact Y happened, proving that Person B lied. Person A wins, continues to go to press calling Person B a liar.