In 1969, Lacey was appointed United States Attorney for the District of New Jersey by President Richard Nixon.

[3] He served until 1971, leading a series of corruption prosecutions against high-profile figures in politics and organized crime, including against Newark Mayor Hugh Joseph Addonizio.

In 1992 he was appointed by United States Attorney General William Barr to investigate whether the Government mishandled a fraud case involving Banca Nazionale del Lavoro.

[2] In 2006, he was appointed to be a federal monitor in an investigation of Bristol-Myers Squibb, centering on the distribution of the drug Plavix.

[3] On April 17, 2017, New Jersey Governor Chris Christie signed an Executive Order directing that both United States and New Jersey flags at state departments, offices, and agencies be flown at half-mast on April 19, 2017, in recognition of Lacey's passing.