Microsoft says sanctions would compromise security
Microsoft says criminals could run rampant if a court backs anti-trust measures proposed by nine states.
The company is continuing its efforts to avoid disclosing Windowscode to third parties.
Microsoft group vice-president of platforms Jim Allchin said the punishment would serve hackers, virus writers and software pirates.
As it stands, the federal anti-trust settlement exempts Microsoft from disclosing information that would compromise security.
The states want the exemption removed on the grounds that sharing technical information would increase competition among software developers.
States' lawyer Kevin Hodges countered Mr Allchin by referring to an interview with Roger Needham, head of Microsoft's English research laboratory. He said the exemption was only meant to protect specific cryptographic keys.
Mr Allchin, the last Microsoft official scheduled to testify in the eight-week-old case, said he disagreed with that interpretation.
Mr Needham was named as a possible Microsoft witness, but was removed from the list last week.
Two experts - an economist and a computer scientist - remain in Microsoft's defence.