The lie that won't die

Amy Goodman:

In May 2010, President Felipe Calderon spoke before a joint session of the U.S. Congress and called for a reinstatement of the assault weapons ban. According to law enforcement officials, 90 percent of the guns picked up in Mexico from criminal activity are purchased in the United States.

Like many before her, she is lying about the denominator.  It may very well be true that 90% of Mexican crime guns that are sent to the BATFE for tracing originate from the US.  But it is a flat-out lie to say that 90% of Mexican crime guns originate from the US. 

If the difference is too subtle for Amy Goodman to understand, let's do an example.  Say there were 1000 crime guns in Mexico.  Of the 1000, only 100 are traceable, so the Federales send these 100 to the BATFE for tracing.  The feds then determine that 90 out of the 100 did indeed come from the US.  Therefore it is correct to say that 90% of traced crime guns come from the US.  However, only 9% of crime guns come from the US. 

By replacing "crime guns sent for tracing" with "crime guns" in the denominator, Goodman is either being lazy or deceitful.  And she's not the first.