The attack occurred in June 2002 when 17 unclassified computers at the laboratory in Botavia, Illinois, were illegally accessed.
The hacker placed music and video files on the labs computer, which internet users could then download. Enquiries revealed that the attacking computer was based in the UK and the Met's specialist computer crime unit was alerted.
The arrested man was taken to a north London police station on 9 July, where he is being bailed to return in mid-August, pending forensic examination of the computers seized from his home.
Police do not believe that any sensitive information was either stolen or accessed during the hacking but enquiries into all aspects of the attack continue.