Has the law ever addressed this "possibility of parole" issue?

On the threads discussing the parole hearings of some of Charles Manson’s Family, there’s been an argument that they have been treated unfairly. Generally, the points being made are this:

  1. They were (retroactively) sentenced to life in prison with the possibility of parole.

  2. The parole boards are stacking the odds against them (by, for example, taking the severity of their crime and victim testimony into account so heavily) so much that their chances of parole are reduced to zero.

  3. Because of this, they have effectively been denied any possibility of parole, which completely contradicts, and renders meaningless, their actual sentence.

This has been debated quite a bit on those Manson threads, but no one, as far as I saw, ever really mentioned whether this has been argued fully before the courts. So I’m asking if it has, and what the results are if so.

[Off-topic: how odd; Firefox says that “renders” isn’t a real word.]