Human beings leave behind DNA wherever we go. We shed skin. We sneeze out DNA-containing droplets. We shed hairs. We can't avoid it.
"You have nothing to fear if you're not going to be a criminal," said a spokesperson for the Bensalem, Pennsylvania police.
The Sixth Amendment to the U.S. Constitution guarantees the right of criminal defendants to fully confront the witnesses and evidence against them. That includes DNA evidence, but it can be difficult to apply that right to the forensic software used to match genetic material from crime scenes to that of a defendant. Why? The software's underlying algorithms, source code, user manuals, internal validation studies and other crucial technical details are trade secrets, often owned by private companies.