Following graduation she practiced products liability, commercial litigation, medical malpractice, and general negligence law with the firm of Dickinson Wright in Detroit, making partner in 1986.

[citation needed] Neilson was nominated to a Michigan seat on the United States Court of Appeals for the Sixth Circuit by President George W. Bush on November 8, 2001, to replace Judge Cornelia Groefsema Kennedy, who assumed senior status in 1999.

On the same day, Bush also nominated Henry Saad and David McKeague to Michigan seats on the Sixth Circuit.

On June 26, 2002, Bush nominated Richard Allen Griffin to a fourth Michigan seat on the Sixth Circuit.

[1] Contrary to Levin's and Stabenow's wishes, Hatch gave Saad, McKeague and Griffin hearings, and passed the three nominees out of committee.

(Fellow Michigan Sixth Circuit nominees Richard Allen Griffin and David McKeague received were confirmed by the Senate in June.)

[3] After being nominated by Bush, Neilson learned that she had myelodysplastic syndrome, a rare blood disorder that eventually required her to undergo a bone marrow transplant in 2003.

Though greatly diminished physically, Neilson returned to work and, following confirmation, moved her chambers to the federal courthouse in Detroit.