It is unknown whether Samsung is defending a patent it had received or whether it has enhanced an existing patent that some other company received before Apple launched its Notification Center. And that is the billion dollar question because Samsung cannot sue for something Google patented. Google recently received a Patent in the U.S. for the Android Notifications Center, but technically, Samsung cannot use that to sue Apple unless it was enhanced by Samsung or if it was sold to Samsung by Google.
Apple launched its Notification Center in 2011 for iOS 5 well after Android models had been shipping with a similar feature. The Notification Center on the Apple iPhone allows the user to drag down a screen that shows emails, texts and weather. Even the most die-hard Apple fan has to concede that Apple's legal team has its work cut out with this suit.
source: inews24 (translate), Brightwire, FossPatents via AppleInsider