05/30/2016 01:36 pm ET Updated May 31, 2017

Feel Free to Wear White Now

A colleague posted an inquiry to the internet about the social norms on wearing white clothing. She wondered if she flouted the protocol of wearing white between Memorial Day and Labor Day, by putting on white jeans this past Saturday -- was she too early?

Her rationale was that she was in the clear, because Memorial Day weekend by definition includes the Saturday preceding the actual holiday. A law professor, she has come up with an excellent example for explaining concepts her students should learn. Daily life demonstrates well technical principles. I am always looking for stories such as hers, because I want people to appreciate how they already are aware of legal reasoning without calling it that. I will add to her situation with analogies to driving and traffic regulations.

Her issue presents the distinction between bright-line rules and standards. Legal norms, and all conventions, come in those two distinct forms. Both can be legitimate. Although people are partial to one over the other if it favors them, we often combine them.

A bright-line rule is more rigid, with less variation from interpretation. It could be deemed objective. If it has exceptions, they also are delineated. A speed limit of 55 is a bright-line rule. Anything below that limit complies; anything above, violates. Rules are easy to administer, not subject to quarrels about implications.

A standard also can be formal, but it is flexible and might depend on circumstances. It would be regarded as more subjective. "You must operate your motor vehicle in a safe, not reckless, manner" is a standard requiring balancing of factors. What constitutes safe depends; even aside from personal preference, it is varies by time of day, weather, road conditions, traffic, etc. Standards can be adapted, producing superior substantive results from at least the authority's perspective.

Norms that rely on numbers belong to the category of rules; norms that refer to words ("reasonable") are along the lines of standards.

A police officer who stops you while you are behind the wheel can cite you for driving 75 or for driving dangerously. You could comply with one rule but not the other rule, driving below the limit but above what is appropriate at midnight in a blizzard over black ice around other cars, or barely above the limit but concededly without any greater risk than at the limit (an argument that does not win over the cop who pulls you over). A bright-line rule seems more strict than a standard. But it is possible to enforce either to a harsh degree.

In my friend's case, the social norm of wearing white only seasonally is -- or was -- well-established. Etiquette guides attest to it. I am sure there are some fashion experts who treat it as a rule rather than standard, while others would take it as a suggestion. Even the absolute version of the bright-line rule allows the bride, but no others, that hue of dress on her special day. My wife advises me that "winter white" is an accepted cheat.

To me, "wear white between Memorial Day and Labor Day" is akin to a bright-line rule. It happens to be one I would disregard, if I wore white at all. But it looks like an admonition, not an aspiration. Even so, I see how practice might have transformed "Memorial Day" to "Memorial Day weekend." Stores have sales honoring "Memorial Day," and nobody takes them to task if they mark down prices on Saturday. The standard, versus rule, form would be expressed as "wear white in the summer."

It doesn't seem the same. To me, it is aesthetically inferior. It lacks the elegance of exactitude.

My friend's concern emphasizes the importance of being exact. Both rules and standards can be ambiguous or exist in multiple versions. Are the markers Memorial Day and Labor Day, or the long weekends celebrated for each? Quite a bit can happen in a day or two. Is the norm, as I was instructed, about shoes and similar leather goods (belts)? Or does it extend to other articles of clothing?

The stakes here are not high. Family and friends are not likely to impose a great penalty on someone sporting white jeans the Saturday before Memorial Day. Her life will continue.

But in many contexts, decisions turn on a word or punctuation mark. That is because they communicate meaning, or miscommunicate it; semantics are not pointless. A contract term has been breached or satisfied if a phrase is read according to one party's intent (as they report it after the fact), but not by the other party's understanding. Whether a tort or a crime was committed is decided by whether an adverb modifies a dependent clause. The Oxford comma matters.

We should care about language. Mindfulness about diction and grammar is not a lawyer's fetish. Scientists are conscientious too. "Accuracy" and "precision" are used neither accurately nor precisely. Accuracy refers to a measurement being true; precision refers to it being reproducible. In a car, a speedometer that is correct half the time but off by three miles per hour the other half the time is accurate to that degree, plus or minus three, but not precise; a speedometer that is consistently, to a fault, wrong by 25 miles per hour is quite inaccurate but equally precise.

To wear white or to wait involves what lawyers term "jurisdiction" and "choice of law." Law is bounded by time and place. Speed limits have been altered over time and change along the same road between urban and rural stretches.

The social norm about wearing white only in the summer may have fallen into desuetude -- a Latinate term for "disuse." Emily Post has relaxed.

My friend's friends, in that virtual network we inhabit nowadays, commented actively on her query. More than a few were unaware that there was any bar against on wearing white during much of the year. Acquaintances chided her for perpetuating immoral class hierarchy. The custom originated with the wealthy, wearing white at their summer home, outside the city, while at leisure. Presumably their help took care of the cleaning. A white outfit makes a man a dandy, a popinjay: witness Tom Wolfe, who was a high-brow documenting the low-brow.

Or it may be that California, with its casual attitudes, lies beyond the reach of this social norm. My wife once scolded me for leaving the house in a sport coat for an evening wedding (instead of a dark suit). When we arrived at the outdoor venue, people were in every type of outfit. I saw shorts.

No doubt other societies have their own admonitions about attire. In China, we are told, a man does not wear a green hat. It indicates he is a cuckold.

This social norm presents another distinction nicely. "Wear white only between X and Y days," is not "malum in se" but "malum prohibitum." Fancy terms are not uniformly pompous. There is a pair, "malum in se" and "malum prohibitum," that have not been improved on for delineating what they do. The former refers to what is evil intrinsically, whatever the actual rule. Murder is "malum in se." The latter refers to what is wrong, because it is prohibited. Driving 125 miles per hour likewise is "malum prohibitum."

My friend generated a lengthy discussion. That shows how law is a social practice. Everyone, laypeople included, engages in legal reasoning. Intellectual engagement is a pleasurable activity.

Her example is useful because it is trivial. It is only about appearances. We can talk without losing our tempers. Our ability to deliberate, not only individually but within a community, is how we set social norms. It is the essence of self-government.