If a virus distributed by you is used to damage or otherwise modify a major system, you can be held accountable. Note that there are different kinds of distribution for viruses. If you simply make a virus available on a web page, and clearly label it as such, then you are unlikely to face any (criminal) consequences.
www.faqs.org/faqs/computer-virus/alt-faq/part3/ www.faqs.org/faqs/computer-virus/alt-faq/part3/
Here are some steps that you can take to help protect yourself from being affected by viruses distributed in Zip files: ... It is very important to have a good anti-virus program installed on your computer. We recommend that you configure your anti-virus program to scan all files that you work with in real time.
kb.winzip.com/kb/entry/20/
 Then the files feed into a malware detection engine, which looks for the signatures of malware such as a virus or a worm.  If we detect any malware when we crawl the site, we can blacklist it and prevent all of the malware the site might deliver, even malware that we have not specifically detected.”...
computersafety.wordpress.com/2009/06/19/block-viruses-d... computersafety.wordpress.com/2009/06/19/block-viruses-distributed-by-web-pages/
A fake email that purports to be from the US Federal Bureau of Investigation (FBI) is circulating on the internet with a computer virus as its payload. The bogus message then asks recipients to ... The latest scam appears to be the first time a virus has been distributed through an email allegedly from the FBI, he says.
akron.co.nz/mb/content/view/38/2/
Close Window E-mail This Page ... Computer Virus Writers Plan Slow Spread; (9/25/2006) ... FBI Warns Of Valentine's Day E-Mail Virus; (2/12/2008)
cbs11tv.com/technology/Storm.Worm.Virus.2.775991.html cbs11tv.com/technology/Storm.Worm.Virus.2.775991.html
Computerworld - A fake e-mail that purports to be from the FBI is circulating on the Internet with a computer virus as its payload. The latest scam appears to be the first time a virus has been distributed through an e-mail allegedly from the FBI, he said.
www.computerworld.com/securitytopics/security/virus/sto... www.computerworld.com/securitytopics/security/virus/story/0,10801,99957,00.html
Virus distributed during college computer sale Jim Huggins; ... This year, a few students got an added bonus: a virus. Four hundred Macintosh systems sold on the first day of the sale had the nVIR virus included on the standard distribution disks prepared by the Information Technology Division (ITD).
catless.ncl.ac.uk/Risks/15.08.html
Subject: Virus distributed on GENTECH ... Date: Tue, 19 Jun 2001 10:21:26 +0200 (CEST) ... Content-Transfer-Encoding: 8bit...
www.gene.ch/gentech/2001/Jun/msg00186.html
The vaccine is a live recombinant vaccinia virus with a gene encoding rabies glycoprotein. This MMWR report details the second human case of vaccinia infection from contact with vaccine bait. In both human cases, contact occurred after a dog got into the bait ... Genetically engineered viruses, distributed from t...
haicontroversies.blogspot.com/2009/11/genetically-engin... haicontroversies.blogspot.com/2009/11/genetically-engineered-viruses.html
In this study, five isolates of Japanese encephalitis virus (JEV) were obtained from swine serum samples collected on Okinawa Island, Japan, between 2002 and 2003. All five JEV isolates belonged to genotype 1, and JEV isolates obtained from the island before 1992 were genotype 3. Genotype 1 was known to be distributed...
www.ajtmh.org/cgi/content/abstract/77/4/737