ANSWER: The term "jurisdictional element" refers specifically to additional explicit language in the statute. So, as you have phrased the question, I think yes, by definition, there is no jurisdictional element if that connection to interstate commerce is not specifically stated in the statute. (That is not to say, of course, that every statute needs a jurisdictional element. Indeed, many things, by their nature, are always in interstate commerce, such that it would be superfluous to include such additional language.)
QUESTION: For example, if there were legislation that barred handguns at weigh stations on interstate freeways, would the inclusion of the location "weigh stations" work as a jurisdictional element (assuming the only possible connection weigh stations have to commerce is in interstate commerce) and obviate the need to include " handguns in interstate commerce" in the phrasing of the law?
ANSWER: I would say "weigh stations on interstate freeways" would probably be a considered a jurisdictional element, yes. It is limited the scope of the regulated activity to a subclass with a closer connection to interstate commerce. Notice, too, that this jurisdictional element might actually bring the regulation into a different category under Lopez--namely, it might render the statute a regulation of the use of the channels of interstate commerce.
QUESTION: Congress is seeking to regulate the substantial effect, so it seems valid to transfer the jurisdictional element from "handguns in interstate commerce" to "handguns at place that is used exclusively for intestate commerce." The Lopez court used the phrasing "nexus with interstate commerce" and it seems as if, in this hypo, the weigh station is as good a nexus as any.
ANSWER: I would generally agree. I would just caution, though, that the existence of a "jurisdictional element" in a statute will not necessarily render a statute a valid use of the commerce power. Jurisdictional elements can come in sorts of different shapes and sizes, some creating a close nexus with interstate commerce and some requiring only a very attenuated one. So it all depends on how much work the jurisdictional element actually does.
QUESTION: For reference: in Lopez the court found that the statute stating "'for any individual knowingly to possess a firearm at a place that the individual knows, or has reasonable cause to believe, is a school zone.'" 18 U.S.C. § 922(q)(1)(A) (1988 ed., Supp. V)" was not within the commerce clause for lack of a jurisdictional element. However, the inclusion of "firearm that has moved in or that otherwise affects interstate or foreign commerce" solved the jurisdictional element problem.
ANSWER: Not necessarily. That was Congress's fix, but the Supreme Court has not held that it was sufficient. So this remains a bit unclear at this point.
QUESTION: If the requirement is that Congress add the phrasing adopted in the second statute, the whole exercise seems rather silly. Can't that just be implied (hello, implied pre-emption!), like so many other things?
ANSWER: I agree, at least to some degree. But again, we are not sure that Congress's fix was sufficient. Moreover, Lopez might have been more symbolic than real. And yes, I think it could be inferred in some circumstances (as mentioned above), but obviously the Court was unwilling to make that inference in Lopez.