Southerlyn often disagrees with McCoy over their trial strategies in cases where she sees the defendant's crime as a by-product of social circumstances, such as homelessness or racism.

There is some nuance in her political outlook, however; she takes a hardline stance against illegal immigration, and sees the Miranda Warning as "trite" and a "hollow formality".

[1] In the 2002 episode "DR 1-102", Southerlyn is brought before the New York Supreme Court, Appellate Division's Disciplinary Committee after promising to get legal help for a murder suspect who had taken hostages, to get him to release his prisoners.

In several episodes, Southerlyn is portrayed as opposing the death penalty, which often puts her in a difficult ethical position when working with McCoy and Branch, who both support capital punishment.

In the 2002 episode "Girl Most Likely," while discussing a gay murder suspect, she notes, "Coming out's got to be a pretty tough thing to do, no matter how understanding your parents are."

In the 2004 episode "Gov Love," she is uncomfortable with a case in which McCoy successfully seeks to have same-sex marriage declared illegal in New York in order to get testimony from a gay defendant's spouse.

"[11] Tim Goodman of the San Francisco Chronicle joined those calling the move a "cheap stunt", adding, "but here's why it didn't work: Anyone who knows anything about gay people knows that no lesbian could ever be that bad of an actress.

"[15] Diane Holloway of the Austin American-Statesman was one of many critics who chose to answer Southerlyn's on-screen question, while citing her as third runner-up for a list of "the most annoying actors on television".

This wide-eyed 'actress' with the tedious monotone nearly ruined one of my favorite series, stumbling through cue cards and generally not acting as Assistant District Attorney Southerlyn for four seasons.

"[21] TV Guide called Rohm "arguably the most inept cast member" in the series' first 18 years,[22] with Ben Katner writing "we are dancing in the streets" upon her departure.

[27] This makes her character, Serena Southerlyn tied with Connie Rubirosa (portrayed by Alana de la Garza) as the longest-serving assistant district attorney in the original Law & Order series in terms of the number of episodes featured (not including crossovers on other shows).