They say there's nothing certain in life but death and taxes. Still, when it comes to prosecuting a criminal case or defending against it, it seemed that DNA evidence was hard to challenge. Now, a team of Israeli researchers shows why we can't be so certain of that either.

As Andrew Pollack reported in the New York Times, Israeli "scientists fabricated blood and saliva samples containing DNA [1] from a person other than the donor of the blood and saliva."

More disturbing, it turns out that civil rights activists who have long railed against governments' desires to collect everyone's DNA in a database for matching against evidence at a crime scene may have been right to worry that the digital DNA profiles in the database could actually be used to fake evidence and frame a suspect.

The scientists "showed that if they had access to a DNA profile in a database, they could construct a sample of DNA to match that profile without obtaining any tissue from that person," writes Pollack. He does, however, note that a way of testing the DNA to see if it has been faked does exist.