The Center’s brief focused on the common-understanding issues identified by the Michigan Supreme Court — specifically, what the ratifiers of the 1963 Michigan Constitution understood the meaning of "just compensation" to be in cases involving eminent domain. The brief examined numerous takings cases from the 19th century to the 1961-1962 Michigan Constitutional Convention and noted that when property owners lost part of their property to eminent domain, they almost universally received compensation that covered the entire loss in property value they suffered. Hence, damages included compensation for any diminution in the market value of the owner’s remaining property due to the presence of the public project for which the land was taken.

The brief noted that where there was a diminution in property value due to a public use without a physical taking, the law was less consistent, but the property owners were typically not allowed compensation. For instance, in 1998’s Spiek v Department of Transportation, the Michigan Supreme Court considered a case where no portion of the owner’s land had been physically taken, but the plaintiff claimed that the construction of a highway near his home had diminished the home’s value. The court held that a diminution in value alone would not constitute a taking and that the property owner could not be compensated for the "highway effects."

In the instant case, MDOT took a strip of the Tomkinses’ property, meaning there was a partial physical taking. Thus, the owners were not seeking compensation for highway effects as a stand-alone claim; rather, they were seeking a consideration of highway effects as a measure of damages for the partial taking.

Such compensation has long been recognized in Michigan’s jurisprudence. Justice Cooley, who has been called Michigan’s "patron saint of constitutional interpretation," indicated in an 1875 case that an owner whose property is not physically taken cannot seek to receive "just compensation" for a constitutional taking, but must rely on whatever tort or statutory remedies are available. But where there has been a partial taking, Cooley concluded, the owner is entitled to full compensation, which includes consideration of the use to which the taken property will be put. Over the next 80 to 90 years, the case law on this point was in almost universal agreement, despite rare cases to the contrary.

When the 1963 Constitution was being debated, this distinction was clearly recognized. For example, some delegates to the Michigan Constitutional Convention sought constitutional language to allow any person whose property was affected by the construction of a road to obtain compensation. Opponents of this language noted that only those whose property was actually taken, in whole or in part, could seek such relief, and these opponents defeated the proposal. The convention essentially chose to keep the status quo.

Thus, both Michigan case law and notes from the constitutional convention indicate that where there is a partial taking, just compensation requires that a property owner be allowed to seek full damages, including consideration of the effect the public project has on the property’s value. If the project diminishes the value of the remainder of the owner’s property, the owner is entitled to compensation for that loss, meaning that the Tomkinses’ request for full compensation should be granted and that the relevant portion of MCL 213.70(2) should be declared unconstitutional.