This article addresses it...
“It amends a long-standing law againt willfully and knowingly trespassing on restricted grounds without lawful authority so that criminal penalties can be applied in a case where a person knowingly trespasses. Willfully has been dropped from the law by the bill.”
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“But readings of the legislative text, federal statute, and legal precedent suggest that the bills supporters are simply unaware of the significance of the bills subtle changes in wording. As always with bills in Congress, its important to look at the potential for how it could be used and abused, not simply the intention of the members of Congress who sponsored it.”
In other words, according to the courts, willful means that you are aware that what you are doing is against some law; knowing means that you are simply conscious of what you are doing.Sorry, I don't see the FEMA boxcars. Yet.