Neela and Gallant make the impetuous decision to get married the same day. Kerry steps in to the Kovac/Clemente battle, encouraging them to get along, which results in a competition to be agreeable. Soon, Abby has her fill of them both, and teaches them a lesson when her patient crashes in CT. Morris, Ray and a somewhat rusty Kerry treat a man with hypothermia, leading Morris to take a stand regarding the best course of action. Luka, Clemente and Sam treat a boy with HIV whose mother refuses to believe HIV causes AIDS. At the days end, Neela and Gallant are married, despite Neelas doubts. At the reception, Luka and Abby celebrate his appointment as Chief of Emergency Medicine, then later decide maybe just friends isnt such a great idea after all.
Season 12 Episode 9 of ER resulted in a 0.00 rating in the 18-49 demographic.
        s12e01 - Caon City
          
        
      
    
        s12e02 - Nobody's Baby
          
        
      
    
        s12e03 - Man With No Name
          
        
      
    
        s12e04 - Blame it on the Rain
          
        
      
    
        s12e05 - Wake Up
          
        
      
    
        s12e06 - Dream House
          
        
      
    
        s12e07 - The Human Shield
          
        
      
    
        s12e08 - Two Ships
          
        
      
    
        s12e09 - I Do
          
        
      
    
        s12e10 - All About Christmas Eve
          
        
      
    
        s12e11 - If Not Now
          
        
      
    
        s12e12 - Split Decisions
          
        
      
    
        s12e13 - Body and Soul
          
        
      
    
        s12e14 - Quintessence of Dust
          
        
      
    
        s12e15 - Darfur
          
        
      
    
        s12e16 - Out on a Limb
          
        
      
    
        s12e17 - Lost in America
          
        
      
    
        s12e18 - Strange Bedfellows
          
        
      
    
        s12e19 - No Place to Hide
          
        
      
    
        s12e20 - There Are No Angels Here
          
        
      
    
        s12e21 - The Gallant Hero and the Tragic Victor
          
        
      
    
        s12e22 - 21 Guns
          
        
      
    ER follows the medical personnel and patients in the emergency room of Chicago's fictional County General Hospital. 
As the doctors and nurses of County's ER confront the daily challenges of a busy urban hospital, including overcrowded waiting rooms, staffing shortages, and the impact of life-and-passing decisions. While they teach the next generation of doctors, the each must tackle demands of their personal lives, at times unsuccessfully. 
The staff is led by Chief of Emergency Medicine Dr. Luka Kovac, a gifted teacher who came to Chicago from Croatia following the tragic passing of his wife and children, but now finds his life on an upswing, and Dr. Kerry Weaver, County's Chief of Staff, a compassionate doctor and uncompromising administrator whose rigid style has isolated her from the medical staff. The ER is staffed by fourth-year resident Dr. Gregory Pratt, who puts patients before procedure, yet fears the responsibility now thrust upon him, feisty nurse Samantha Taggart a tough single mother attempting to balance her difficult personal issues with her demanding professional life, and Scott Grimes as the less than capable Chief Resident Dr. Archie Morris, along with a trio of second year residents: Dr. Abby Lockhart a former ER nurse turned doctor, building a new career and a new life that has taken a sudden and unexpected turn, Dr. Neela Rasgotra recently married and finding her role in the ER after a long period of uncertainty, and Dr. Ray Barnett who must make the choice between his career as a doctor and the rock band in which he plays. Featured this season as recurring characters are John Leguizamo as the innovative, and problematic, Dr. Victor Clemente, Kristen Johnston as demanding Nurse Manager Eve Peyton, and Leland Orser as the ER's highly individual surgical attending, Dr. Lucien Dubenko.