In the aftermath of 9/11, several cast and crew members volunteered to help the rescue effort. The main title voiceover by Steven Zirnkilton was also changed for the first few episodes to include the following dedication: "On September 11, 2001, New York City was ruthlessly and criminally attacked. While no tribute can ever heal the pain of that day, the producers of Law & Order dedicate this season to the victims & their families and to the firefighters & police officers who remind us every day with their lives & courage what it truly means to be an American". Syndicated airings of the episodes replaced this dialogue with the original title voiceover. The opening sequence changed as well; NBC ordered the opening credits for the third season re-edited to remove images of the World Trade Center, which were seen at the beginning and ending; the credit sequences in the previous two seasons were not subsequently changed.

With David J. Burke having left the show at the end of the second season, Neal Baer was the sole showrunner / executive producer of Season 3. During the production of the third season, Baer convinced Amanda Green to begin writing scripts. Green was already serving as a consultant for the series while she worked for the NYPD. The episode "Counterfeit" became her debut as a writer. Tara Butters and Michele Fazekas who also joined the writing staff in the third season enjoyed the freedom of not having to meet with a large team in a writer's room. "As a result, there was no sense of competitiveness. We were working on our own so it was like writing your own mini-feature.