After three seasons playing the buttoned-down lawyer on "Law & Order,” Hennessy asked to leave the series to try her hand at other ventures. Fearful of becoming typecast as ultra-serious and subdued because of her TV persona, the actress turned to comedy to undertake the thankless role of a predatory architect with designs on married construction worker Greg Kinnear in the cutesy "A Smile Like Yours" (1997). In 1999, Hennessy displayed her versatility as the patient lover of an Indian woman who has decided to act as a surrogate mother for her sister in "Chutney Popcorn.” She then portrayed the doctor who was able to turn an autistic woman into a genius in the fable-like "Molly" (also 1999). The actress returned to TV once again playing a lawyer, this time one assisting in the prosecution of Nazi war criminals in the acclaimed 2000 TNT production "Nuremberg.” Hennessy next portrayed First Lady Jacqueline Kennedy in the miniseries "Jackie, Ethel, Joan: The Women of Camelot" (NBC, 2001) and was seen on the big screen as a cop in the actioner "Exit Wounds" (2001).
In the fall, the performer returned to the weekly series grind, this time headlining the NBC drama "Crossing Jordan” (2001- ) Cast as an unconventional medical examiner who has returned to her hometown of Boston, Hennessy's Jordan Cavannaugh was a dedicated if impetuous person who often went beyond the call of duty looking for clues. Working well with a cast that included Ken Howard (as her father) and Miguel Ferrer (as her boss), the actress had a chance to create a complex, intelligent female character that audiences seemed to embrace. While she had committed to the small screen, Hennessy continued to seek out intriguing feature roles as well. She co-starred in the romantic comedy "Love in the Time of Money" (2002), a dark comedy set during the Nasdaq boom of the late 1990s about nine New Yorkers from all walks of life who are linked by romance and commerce.
Hennessy was game for anything when NBC decided to do a two-arc crossover of “Crossing Jordan” and the glitzy “Las Vegas” (NBC, 2003- ). She was brought together with the cast of the other series when the body of a con man found in dead aboard a Montecito Hotel and Casino airplane in Boston. Meanwhile, Hennessy gained wider exposure in “Wild Hogs” (2007), a big, dumb and hugely successful comedy about four down-and-out men (John Travolta, Tim Allen, Martin Lawrence and William H. Macy) going through respective mid-life crises who embark on a freewheeling, cross-country motorcycle trip in order to prove their manhood. Hennessy had the thankless role of a devoted and affectionate wife of a dentist (Allen) trying to look cool for his son (Dominic Janes). Despite scores of bad reviews, many of which complained about the bizarre, almost obsessive need for the four leads to constantly prove their heterosexuality onscreen, “Wild Hogs” dominated the box office its opening weekend, taking in almost $40 million and making it the first bona fide hit of 2007.