The Volokh Conspiracy

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Volokh Conspiracy

Corpus linguistics and the temporal difficulty in statutory interpretation


Judges sometimes make reference to the temporal aspects of interpretation and insist that they are seeking the meaning of the text at the time it was drafted. Yet in practice, judges often ignore the temporal aspect of interpretation or attempt to address it using tools of questionable utility, such as historical dictionaries. Our linguistic intuition about usage and meaning in our own time and our own speech community can be highly unreliable. But this problem is amplified when we are interpreting a text that dates from a time from which we have no linguistic memory or experience. And historical dictionaries, like their contemporary counterparts, set forth a range of possible meanings of a given word but cannot be relied upon to show the ordinary meaning of a given word in a particular context.

We can see this play out in the evolving scope of the word "vehicle." The "no vehicles in the park" problem seems a mandatory subject for any serious treatment of statutory interpretation. It was introduced initially by Professor HLA Hart in his famous debate with Professor Lon Fuller. Hart says that "[p]lainly" the rule "forbids an automobile," but asks what about "bicycles, roller skates, [and] toy automobiles"? (The airplane example invokes an actual case— McBoyle v. United States, in which the Supreme Court held that an airplane was not a vehicle under the National Motor Vehicle Theft Act.)

Commentators continue to opine on the "no vehicles" problem. In their text, "Reading Law," Justice Antonin Scalia and Bryan Garner say that the Hart prohibition should extend to any "sizable wheeled conveyance," and thus to automobiles—including "ambulances, golf carts, mopeds, motorcycles, and (perhaps) Segways"—but not "remote-controlled cars, baby carriages, tricycles, or perhaps even bicycles." Professor William N. Eskridge Jr., in his recent text, "Interpreting Law," disagrees with Scalia's assertion as to bicycles; he says that "bicycles are commonly considered vehicles."

The scope of the word "vehicle" is relevant in discussions of legal interpretation today. It was relevant at the time of the Hart/Fuller debate in the 1950s. And it was relevant in McBoyle, which interpreted a statute enacted in 1919.

We do not propose to answer the "no vehicles" problem here. Instead, we use the problem to illustrate one way (certainly not the only way) in which historical corpus data can be used to illustrate ordinary meaning at a given point in history.

One way to examine the range of possible uses of a word and the lexical environment in which it occurs is to look at collocation. With respect to contemporary usage, we can view the most common contemporary collocates of "vehicle" in the NOW Corpus.

electric, motor, plug-in, unmanned, armored, connected, cars, aerial, charging, pure, launch, owners, hybrid, traffic, fuel, driving, gas, autonomous, struck, operating, road, safety, accidents, battery, ownership, emergency, batteries, emissions, seat, advanced, driver, primary, demand, gmv, commandeered, fuel-efficient, uavs, automakers, demonstrators, excluding, lunar, passenger, fleet, gasoline, luxury, drove, parking, retirement, vehicles, infrastructure

Many of the collocates of "vehicle" in the NOW Corpus strongly indicate "automobile" as a likely candidate for the most common use of "vehicle." (A supposition we would need to confirm with key word in context [KWIC] data). The NOW Corpus lists a number of automotive collocates (like "motor," "car," "traffic," "fuel," "driving," "gas," "battery," "parking" etc.) Some of the collocates by themselves have a range of possible uses ("owners," "operating," etc.), but when examined in the key word in context (KWIC) in the environment of "vehicle," these almost always indicate an automotive meaning. "Airplane" doesn't appear, though two particular types of aircraft are attested—unmanned aerial vehicles (drones) and spacecraft. Similarly, "bicycle" doesn't appear.

We can also examine the collocates of "vehicle" during the 1950s, the decade of the Hart/Fuller debate, in the COHA.

motor, space, trucks, moving, wheeled, tax, self-propelled, passenger, unit, tracked, orbit, test, b.g., launching, highways, tanks, license, robot, emergency, units, taxes, streets, equipment, manned, armored, vehicles, fees, vehicle, traveling, operate, loaded, fuel, commercial, driver, ride, traffic, designed, weight, speed, cars, carrying, operation, unsafe, horse-drawn, high-powered, amphibious, administrators, tactical, registration, delivery

The meaning of "vehicle" evolved significantly from this period, though the automotive use of "vehicle" still predominated. And, again, none of the top 50 collocates of "vehicle" include the notion of "airplane" and "bicycles."

With respect to the McBoyle case, because the statute at issue in McBoyle was enacted in 1919, and because the COHA allows us to search only in 10-year increments, it may make sense to include data from the decades of 1910 through 1930. The collocate data from this period (consistent with the collocate data above) allow us to draw a similar inference that the automotive use is the most common use of "vehicle," and that the "airplane" and "bicycle" sense remain unattested.

motor, horse-drawn, wheeled, horses, pedestrians, kinds, expression, sqdriver, passing, moving, various, horse, automobiles, tax, heavy, drawn, carry, roadless, rickety, trucks, communication, approaching, traffic, electric, mental, physical, 3500000, astral, belonging, steam, transportation, commissioner, rear, total, carrying, propulsion, propelled, oncoming, carriages, registration, ego, conceivable, tires, drivers, vehicle, carriers, 45, loaded, halted, manufacturers

It should be noted that only a few of the collocates in their period occur more than once, and only four—"motor," "horse-drawn," "wheeled" and "horses"—occur 10 times or more, with "motor" occurring twice the number of times as the other three combined.

From this data, we can make a few preliminary observations (observations that we can later confirm by reviewing KWIC data.) First, the collocates of "vehicle" strongly suggest that the most common use of "vehicle" is with reference to automobiles. Second, the absence of "airplane" and "bicycle" in the top 50 collocates of "vehicle" raises an important question about ordinary meaning. If we accept that the necessary and sufficient conditions of "vehicle" are "a means of carrying or transporting something," then there seems little question that both an "airplane" and a "bicycle" are possible readings of "vehicle." But can a given use of a word be ordinary if it is possible, but unattested? (In our article, we confirm that "bicycle" as "vehicle" is rare, but attested in other corpus data. "Airplane" as "vehicle" is not.)

This is merely an illustration. An analysis of the use of "vehicle" during a given time period or an assessment of the ordinary meaning of "vehicle" in a particular historical statute would require a much more granular review of KWIC data from the corpus. But the illustration demonstrates that over the decades the range of possible meanings of the term "vehicle" has changed dramatically. The possible uses of "vehicle" are reflected with different frequencies at different points in time in the corpus. The question of the possible meanings of "vehicle" would have a different set of answers based on the date in which the statute was enacted. Our intuition alone cannot tell us when spacecraft or unmanned aerial drone became possible answers to this question, nor can our intuition tell us at what point in history (if ever) horse-drawn buggy was no longer a likely or viable answer.

We have no introspective access to historical usage from periods for which we have no linguistic experience or memory. To the extent that the law wishes to take into account the meaning of a text at the time of its enactment, some empirical measure of historical usage is necessary and corpus linguistics presents itself as an attractive option.