The right not to be unfairly tried is easily satisfied by not having a trial at all.

The right to a fair trial is about two things: you must be tried before being found guilty and punishment/sentencing is administered, and that trial must be executed fairly. In effect, you have the right to a (fair) trial.

A trial and especially a fair trial are undeniably interventions on how things would otherwise proceed. But I agree with moomin that the positive/negative distinction is not really meaningful.