Casey Novak gets beaten up in “Night” , which is Season 6, Episode 20 of Law & Order: SVU.

Episode details

  • Title: Night
  • Season/Episode: Season 6, Episode 20
  • Air date: May 2, 2005

What happens

In that episode, Novak is attacked by a masked assailant in her office, and the storyline later notes that she is badly beaten and sent to the ICU.

TL;DR: If you mean the episode where Casey Novak is beaten up, it’s “Night” (S6E20).