Apple is suing Samsung, claiming its mobile phone and tablet product lines copy Apple's iPad and iPhone devices.
In a lawsuit filed at the US District Court for the Northern District of California, Apple alleges Samsung's Galaxy smartphones and tablet design features violate its trademarks and patents.
In statements released to Reuters, Apple says previous versions of Samsung's smartphone features did not resemble Apple's. A spokesman said: "This kind of blatant copying is wrong."
Samsung says it will take "appropriate legal measures" to protect its intellectual property.
Growing tablet market
The latest report by Strategy Analytics predicts tablet sales will reach $49bn (£30bn) in four years' time.
Neil Mawston, director at Strategy Analytics, said: "We forecast global tablet wholesale revenues to surge from zero in 2009 to $49bn in 2015. Tablets are a high-value casual-computing segment that is creating huge growth opportunities for major brands such as Apple and Samsung."
Research firm Context says a lot more tablet devices are being bought by businesses, with overall tablet sales up 910% in the most recent quarter.
Apple sued Motorola in November 2010 over touchscreen patent claims.