Samsung Electronics Co told jurors that its products are not copycats of Apple Inc's iPhone but rather an example of legitimate American-style competition from the South Korean company.

Lawyers for both tech giants faced off on Tuesday for opening statements in the highly anticipated US patent trial, where Apple has accused Samsung of stealing iPhone features like scrolling and multi-touch.

The stakes are high: Apple is being tested on its worldwide patent strategy against Google's Android operating system, while Samsung faces the threat of sales bans on its Galaxy line of phones and tablets.

Apple attorney Harold McElhinny said Samsung's own internal product analyses show it deliberately chose to rip off the iPhone, but Samsung lawyer Charles Verhoeven said all firms produce such documents.

"It's called competition," Verhoeven claimed. "That's what we do in America."

The world's largest consumer electronics corporations have been waging legal war around the world, accusing each other of patent violations as they vie for supremacy in a fast-growing market for mobile devices. They sell more than half of the world's smartphones.

The legal fight began last year when Apple sued Samsung in a San Jose, California, federal court, accusing the South Korean company of slavishly copying the iPhone and iPad. Samsung countersued.

The federal courtroom in San Jose was jammed on Tuesday with lawyers and reporters. Both companies relied on slides featuring various phone models, internal e-mails and news reports to make their points.

McElhinny showed slides that featured old Samsung phones from 2006 and compared it with the Korean company's newer smartphones from 2010.

The key question, McElhinny said, would be how Samsung moved from the old phones to "these phones." And even though Apple is a successful company, he said, it must defend its rights when someone steals their property. Samsung has sold 22.7 million smartphones and tablets in the US, reaping US$8.16 billion in revenue, he said. Apple is seeking damages of more than US$2.5 billion.

Samsung's Verhoeven countered that many iPhone features, like its popular minimalist design, had already been thought up by others before its release.