Gwyneth Paltrow's "reckless" behaviour at a ski resort in 2016 resulted in a man sustaining permanent brain injuries, a US court has heard.

The Oscar-winning actress is being sued by retired optometrist Terry Sanderson, who alleged that she skied "out of control" and hit him at Deer Valley Resort in Park City, in Utah.

Ms Paltrow appeared in court for opening statements in the case, wearing a high-necked cream jumper and brown trousers.

Lawrence Buhler, representing Mr Sanderson, told jurors that Ms Paltrow's behaviour on the mountain in 2016 had been "reckless".

"Ladies and gentlemen... distracted skiers cause crashes. Defendant Gwyneth Paltrow knew that looking up the mountain and to the side while skiing down the mountain was dangerous," he said.

"(She) was looking somewhere else blindly skiing down a mountain while looking up... (this) was reckless."
Mr Buhler added that an injury being caused was "not a matter of if, but when" and that Ms Paltrow "knew what she was doing was dangerous".

He went on to tell the jury that the actress' "neglect and conscious choices" had combined together to cause Mr Sanderson "four broken ribs and permanent brain damage".

The court heard that Ms Paltrow considered herself an "intermediate" level skier.

Mr Buhler added that following the collision, the actress had not said anything to Mr Sanderson, but had "bolted" away down the mountain.

He said that for a year following the incident, his client had made multiple visits to medical professionals and displayed symptoms of "persistent brain injury".

"Before this crash, Terry was a charming, gregarious outgoing person," Mr Buhler said.

"He was living a full life travelling the world, doing everything possible to enjoy life and guard his health... but after the crash, he is no longer charming."

The defence is seeking damages of up to $3,276,000, Mr Buhler said.

Ms Paltrow has filed a counter-claim, alleging that Mr Sanderson had hit her and delivered a full "body blow" and is seeking damages of one dollar.

Stephen Owens, representing Ms Paltrow, said the actress was a "conservative" skier and had been "freaked out" when she had collided with Mr Sanderson.

"You'll never hear the words hit and run," he told the court in his opening remarks.

"This was not a hit and run. The plaintiff even had a ski expert evaluate it and he said it's not a hit and run - take that out of your mind.

"Gwyneth was hurt by Mr Sanderson's negligence... she is upset. Anyone sustaining a blow is upset, she is sore, she never went to a doctor...but it rattled her and it physically hurt her."

Producing a one-dollar bill in court, Mr Owens said: "We ask you for a dollar. This is a lot to go through for a dollar... so she came for a family vacation, half the afternoon was kind of ruined, so that dollar is important to us, to my client."

Both Ms Paltrow and Mr Sanderson are scheduled to give testimony at the trial, which is set to last eight days.