He was the son of United States Supreme Court Justice Samuel Nelson.

[2] Following the admission of the State of Minnesota to the Union on May 11, 1858, Nelson was nominated by President James Buchanan on May 20, 1858, to the United States District Court for the District of Minnesota, to a new seat authorized by 11 Stat.

He was in the midst of a trial when he astonished every one by dismissing the jury, adjourning court, and announcing his retirement to private life.

[7]Following his retirement from the federal bench, Nelson resumed private practice in Saint Paul from 1896 to 1904.

[10][2] On November 2, 1858, Nelson was married to Mrs. Emma Fuller (née Beebee) Wright (1832–1886).