The premium cabler is making a weekly commitment to nonfiction. HBO said today that Monday nights will feature original documentaries year-round, including “timely encore presentations.” The announcement comes several months after HBO signed a multi-year deal with Susan Lacy, creator and executive producer of PBS’ American Masters series, to produce and direct docus. The cable channel kicked off the new Monday tradition last week with The Case Against 8, about the Supreme Court’s overturn of California ban on gay marriage, and continues tonight with 112 Weddings, in which a videographer tracks down couples whose nuptials he filmed. Future subjects include President Nixon, Pamela Smart and Russia’s anti-gay laws.