So, it's a French movie, from the early 90s (possibly 1993 or 1994), which I saw more than 20 years ago.
Here are a few screenshots: https://imgbox.com/b8nbyXdU Apparently it starred Alain L'yle and Anastasia, and it was directed by Marc Landers.
Apparently it was released in Spain under the title "Triangulo erotico". See here old ad with the VHS in a second hand shop: https://www.todocoleccion.net/coleccion ... x169723936
It was also available from Italian streaming sites with the title "L'avvocatessa senza mutande" (the lawyer without panties). It is, however, no longer there.
Almost sure the "Anastasia" is Anastasia [3], however none of the movies listed seem to be this one.
The plot, as I can vaguely remember it, was something like this: The plot is like this: a female lawyer (Anastasia) goes to prison to visit her client (an old guy). She goes to prison without panties and while she is being fucked by the guy inside the cell, other prison inmates look. Actually, another prisoner (a guy) does a blowjob to a prison guard. There were other scenes: at least one lesbian scene and a threesome with the wife of the prisoner.