But this was just a prologue to an era in which the hoodie became at once an anodyne style object and a subject of moral panic, its popularity and its selective stigmatization rising in proportion. A glance at almost any police blotter, or a recollection of the forensic sketch of the Unabomber, will confirm the hoodie as a wardrobe staple of the criminal class, and this makes it uniquely convenient as a proxy for racial profiling or any other exercise of enmity. The person itching to confirm a general bias against hip-hop kids or crusty punks imputes crooked character to the clothing itself.

Which brings you to the transcript of the 911 call made by Trayvon Martin’s killer. Dispatcher: ‘‘Did you see what he was wearing?’’ George Zimmerman: ‘‘Yeah. A dark hoodie, like a gray hoodie.’’ Triv­ial details can bear serious import. Surely there would have been demonstrations after the killing and the killer’s acquittal regardless of what the victim wore. As it happened, those demonstrators — legislators on chamber floors, marchers in the street — picked up the sweatshirt as an emblem, donning hoods in solidarity. Instantly a symbol aggrieved at having to be one, the hoodie was jolted into a curious space: Where the basic hoodie means to defend against the elements, the protest hoodie seeks to offend the right people. In the paranoid view of stodgy shopkeepers, the hoodie is to be feared for extinguishing individuality; in its politicized life, it mutes identity to signal alliance, not unlike a resistance group’s uniform.

All that potential subtext is attached to a generally evocative item of clothing. The white working-class hoodie still glows with the Rocky Balboa ideal of grit and tenacity. The yoga-class hoodie is sold on a promise of snuggly virtue that may explain why in Saskatchewan they call the thing a ‘‘bunny hug.’’ The tech-sector hoodie made default by Facebook’s Mark Zuckerberg carries on the garment’s proud juvenile tradition of informality and defiance. Once perceived as an affront to professionalism, it has since settled in as a convention.

In January, there emerged a debate in the business press regarding the rituals of dress in the tech industry and their relationship to the field’s hospitableness to women. The argument proceeded in an article on Quartz headlined ‘‘The Subtle Sexism of Hoodies’’ and in counterarguments suggesting, for instance, that ‘‘hoodies represent a rejection of old ideas and an openness to new ones.’’ I was struck by the ready acceptance of the notion that a Silicon Valley hoodie was not just a prerequisite in its field, like Gucci loafers on Wall Street, but also a costume of dominance. Its visual strength abets its powers as a cultural marker, needing just a nudge to create its own contexts.

You must have seen a sitcom or TV commercial in which black actors wear hoodies in new millennial colors — mustard, maroon — to portray coders. In a current General Electric ad, for example, the costume functions as characterization, and the cheery color of the cotton somehow trumps that of the skin in terms of mass iconography. But the ascent of casual wear does not quite disguise the unchanging strictness of social codes, and the hood continues to frame matters of class and race in ways that tend to satisfy the interest of power. The lingering question of the hoodie is simply: Who enjoys the right to wear one without challenge?