Turner Surkov on Monday at 9 a.m. was

Turner Surkov on Monday at 9 o´clock in the morning was removed from work by the foreman of the site, as Surkov´s hands were shaking and he smelled of alcohol. Three days later, Surkov was dismissed under paragraph 6 (b) of Art. 81 of the Labor Code of the Russian Federation. Surkov appealed to the court for reinstatement, indicating in a statement that, firstly, he drank not at work, but at home on Sunday.
Secondly, he worked for ten years in this organization and was never brought to disciplinary liability; thirdly, the site master dismissed him from work by oral order.
What evidence is taken into account to confirm the fact of the employee being drunk? What is the basis and procedure for terminating an employment contract in accordance with clause 6 (b) of Art. 81 of the Labor Code of the Russian Federation?