According to one LEO, as long as you have to physically manipulate the blade, rather than a separate mechanism such as a push button or slide, it is considered assisted and legal.
That was in the Pittsburgh area and although it is true by the law (though it is vague and has other restrictions) it may not be representative of the average LEO understanding.
EDIT: this was in regard to a Kershaw Leek, that I showed the LEO.