The Libertine, though set in the 17th century, does not follow traditional period film conventions (a la A Cock & Bull Story). It could hardly be described as a costume drama; it has none of the restrained formalities of the genre. Ornate sets are replaced by murky taverns and dark back-streets.
Also, the camera is frequently hand-held, which, combined with Rochester's atheism and amorality, gives the film a feeling of contemporariness in both style and tone.