Justice can’t flow down like water if justices treat mere wetlands as if theyare mighty streams.

In a decision due this month, the U.S. Supreme Court will rule on two conjoined cases about the limits of Congress’ power to "regulate commerce … among the several states." The repercussions of the decision will be profound.

At stake is the preservation of state regulatory authority (as opposed to federal authority) and, more importantly, the protection of individual property rights.

The power to regulate commerce also carries with it the power to regulate the avenues of commerce, such as roads and (by precise legal language) "navigable waters." Congressional action and court cases through the years have broadened that authority to include the ability to safeguard not just the navigability of waterways but also their ecological health.

Hence, it was through the above-cited Interstate Commerce Clause of the Constitution that Congress asserted the power to pass the Clean Water Act and to delegate enforcement authority to the Army Corps of Engineers. At issue in the two pending cases, however, is whether that power extends to regulation of property that sometimes features standing water that the Corps considers ecologically useful, even if that water is nonflowing, non-navigable, not commercially usable and not interstate but instead entirely contained within one state.

Even if the Corps is deprived of the ability to regulate the use of the isolated wetlands at issue, the state governments still retain the authority to do so to protect the public’s health or welfare. As recently as 2001, the Supreme Court reaffirmed "the States’ traditional and primary power over land and water use." If they were sensible, Congress and the already-overburdened Corps might even welcome the chance to leave to state supervision those remote wetlands that clearly have no commercial impact.

This is especially true when, as the petitioning landowners noted in their final reply brief, "the grant ofsuch authority to the Corps would, in many cases, deprive persons of their property rights … ."

In the first case, known as Rapanos v. U.S., one of the Rapanos’ wetlands at issue is some 20 miles from the nearest navigable waterway. Rapanos’ attorneys note that surface water runoff is "only intermittent" and is connected to the primary navigable water (Saginaw Bay) only "by means of a man-made drainage ditch … [which leads to] a non-navigable creek and a river that becomes navigable [only] at some point downstream." Neither the wetlands at that site nor at Rapanos’ two other sites at issue "are physically adjacent to [i.e., abut] a traditional navigable waterway. Nor was an actual discharge into traditional navigable waters proven or even alleged."

Instead, the Corps claimed authority over all water that has "any hydrological connection" to a waterway that is actually navigable, no matter how indirect the link. The Corps’ reasoning sounds somewhat akin to that of a podiatrist who claims authority to treat an optical cataract because the foot is connected to the ankle and then to the leg, et cetera, all the way up to the eye socket. What’s particularly galling is that the Corps would use that broadly defined authority to forbid a landowner from improving his own property.

In the second case, Carabell v. U.S. Army Corps of Engineers, the Corps doesn’t even claim there’s proof of a "hydrological connection" to any navigable or interstate waterway. The wetland in question is separated from a man-made ditch by a half-century-old berm — and then, as in the Rapanos case, the ditch empties into a series of other, non-navigable (and noncommercial) watery avenues that finally reach a navigable lake.

Nevertheless, the Corps denied the Carabells the right to fill those completely self-contained wetlands because the wetlands’ proximity to the ditch (on the other side of the berm) made it qualify as "adjacent" to the ditch, according to the Corps’ own "regulatory definition" of "adjacent" — which is all the Corps says is needed in order to invoke regulatory authority.

Arguing for the U.S. Government, Solicitor General Paul Clement cites court precedential chapter and regulatory verse to support the powers claimed by the Corps on behalf of Congress. Lawyers for the landowners answer equally strongly with their own, diametrically opposing interpretations of the exact same clauses of the exact same court precedents.

But what’s needed is common sense: If water can’t support a floating vessel, then by definition it’s not navigable. If the waterway in question isn’t used for trade or other business, then by definition it’s not used for "commerce."

Surely Congress itself pushed some definitional limits when it wrote the Clean Water Act, and in these cases the Corps seems to assert an even greater testing of those limits. Yet words have real meanings, and the powers of Congress were specifically enumerated so as to say "thus far and no farther" because powers not enumerated for Congress were (by the Tenth Amendment) "reserved to the States respectively, or to the people."

The high court may, but ought not, split legal hairs by approving the regulations against Rapanos while striking down those against Carabell (or vice versa). It ought to rule against the Corps in both cases, thereby keeping tyranny at bay.

Examiner columnist Quin Hillyer is executive editor of The American Spectator.