Brittney Griner's attorney presents doctor's letter in court, says she had permission to use cannabis

Brittney Griner's attorney presented new evidence on the fourth day of her trial in Russia, where the WNBA star has been detained for nearly five months.

The lawyer had a letter from an American doctor giving Griner permission to use cannabis to reduce chronic pain.

Griner was expected to testify but her testimony was delayed until July 26 at the request of her legal team so she can have more time to prepare.

Griner, a two-time Olympic gold medalist, was visiting Russia to play basketball in the off-season when she was detained at Sheremetyevo International Airport after being accused of having vape cartridges containing hashish oil, which is illegal in the country.

If convicted, Griner, 31, faces up to 10 years in prison and also has a right to an appeal.

Griner pleaded guilty on drug charges in court last week, saying that the vape cartridges containing hashish oil were in her luggage mistakenly.

Griner, who has been detained in Russia since Feb. 17, said she had no "intention" of breaking Russian law and did not mean to leave the cartridges in her bag.

Her legal team told ABC News in a statement last week that her "guilty" plea was recommended by her Russian attorneys.

"Brittney sets an example of being brave. She decided to take full responsibility for her actions as she knows that she is a role model for many people," they said in the statement. "Considering the nature of her case, the insignificant amount of the substance and BG's personality and history of positive contributions to global and Russian sport, the defense hopes that the plea will be considered by the court as a mitigating factor and there will be no severe sentence."

Her trial, which is taking place in Khimki, a suburb of Moscow, began on July 1 as the U.S. government works to secure her release.

At the trial on Thursday, several Russian individuals testified as character witnesses about their experience with the Phoenix Mercury player, who also played in the WNBA offseason for UMMC, a Russian basketball club in the city of Yekaterinburg.

The first witness was Maxim Ryabkov, the director of UMMC. The second witness was team doctor Anatoly Galabin, who said that Griner never tested positive for doping while playing for the team. A third witness, Evgenia Belyakova, one of Griner's Russian teammates, said that Griner was the leader of the team.

The U.S. government classified Griner's case on May 3 as "wrongfully detained."

White House press secretary Karine Jean-Pierre told reporters last week that Griner's guilty plea will have "no impact" on any of the negotiations to bring her home.

Calls to free Griner escalated following the release of U.S. Marine veteran Trevor Reed last month, who was freed from a Russian prison as part of a prisoner exchange. Former Marine Paul Whelan has also been detained in Russia since 2019.

"We're going to do everything that we can to bring home Brittney Griner safely, and to also make sure that we bring Paul Whelan back home, as well," Jean-Pierre said.

ABC News' Joseph Simonetti, Tanya Stukalova, Patrick Reevell and Henderson Hewes contributed to this report.