Lee was found not guilty in February of accounting fraud and stock manipulation by a Seoul Central District Court but the prosecutors appealed the ruling.
The appeal hearings, which wrap up on Monday, come at a time when Lee faces growing questions about his ability to lead Samsung, the world's top memory chip and smartphone maker, as it grapples with slowing profits and falling stock prices.
Lee and other former executives had been accused of engineering a merger between two Samsung affiliates - Samsung and Cheil Industries - in a way that dealt poorly with the interests of minority shareholders.
Prosecutors allege Lee prioritized personal gain as Samsung's de-facto leader during the merger, harming shareholders and investors.
Lee, a third-generation leader of the Samsung Group, has been dogged over the past decade by lawsuits, jail time and attacks from foreign hedge fund Elliott over the 2015 merger of the affiliates that helped tighten his grip on the sprawling conglomerate, after his father was hospitalised due to heart attack in 2014.