The case against her was weak enough. Did her defense have to mock the very idea of invisible injuries?In March, on Day 7 of the Gwyneth Paltrow ski trial, after the court spectacle had already been branded everything from a “meme machine” to “the whitest trial of all time,” the retired optometrist Terry Sanderson sat in the witness box, somewhat deflated already. By that point, he probably knew that his pursuit of Paltrow for damages connected to a ski collision he said was her fault was a pretty bad idea. Sanderson claimed that injuries he sustained during the 2016 ski crash (including, notably, a concussion) changed his life, turning him into “a different person,” and “a crippled vet.” Paltrow’s lawyer, the languid, unflappably stone-eyed Stephen Owens, stood before him, presenting Facebook posts — a lot of Facebook posts, some taken months after the collision — as evidence of robust health.“This is a picture of you and your girlfriend, smiling big, right?”“Smile, camera, yup,” Sanderson replied.And then, the deluge:Was this, Owens asked, Sanderson hiking with his girlfriend? Was this him taking a picture of a moose? Was this him, looking happy? Was this him hiking again, and smiling? With a cool backpack containing water? Scuba diving? At an auto show in Germany? A shooting range? BMX bike show? Was this Sanderson on a boat ride along canals in the Netherlands? Did he do bus tours? Or go to Morocco? Twice? Did he go to the this museum in Marrakesh? Was this him at a rock concert? At a ski resort? Out with drinking buddies? At an exhibit? Feeling happy? Looking fit and happy? Was this him “doing yoga, or momba, or what?”“It’s Zumba,” Sanderson corrected. And yes.As far as controversies go, the trial was as Diamond Life as you can get. For about a week, it lived in the media as a jaunty low-stakes holiday from the high-stakes everything of our ongoing decennium horribile. Amid a news cycle of war and school shootings, recession and an indicted former president, it was an almost-delightful diversion to have this little legal whodunit, this simple question of who crashed into whom on a resort ski slope so luxurious it might as well be covered in cashmere.As much of a trifle as the trial was for viewers, it seemed to be a real inconvenience for Paltrow, who said she was injured by Sanderson and infamously claimed to have “lost half a day of skiing” as a result of the crash. Sanderson seems to me like an opportunist with an appetite for attention, or at the very least a schlemiel, possibly a little vain. The retired optometrist, the jury made clear, crashed into Paltrow, making him the offender. Unsurprisingly, she won the case.But what frustrated me in this trial, particularly in the questioning above, was that Sanderson’s claim that his life was changed by the concussion was over and over again challenged or dismissed. Part of the reason for this assertion seemed to stem from the fact that, well, he seemed to still have a life. Owens heavily implied that a man truly affected by a mild traumatic brain injury like a concussion couldn’t or wouldn’t go hiking, or travel, or make it look on Facebook as if he were living the dream. Or maybe the frame of reasoning was more that somebody living with illness — in Sanderson’s case an invisible illness — shouldn’t be doing those things. He should be in bed, in the land of the sick, no visa, no passport.The category of invisible illness — which means exactly what it sounds like: an illness or disability not immediately apparent — is growing sharply in America. Through the wonders of medicine we’ve become great at turning life-or-death illnesses, like diabetes, heart conditions or certain forms of cancer, into chronic conditions that can often be lived with. At the same time, diagnoses of hidden diseases like Crohn’s or fibromyalgia are becoming increasingly common — as is long Covid, which on its own might have affected as many as 23 million Americans.The sociologist Arthur W. Frank has called this cohort ‘remission society.’ But I prefer to think of it as a society of walking wounded.Sanderson is really not a representative whom anybody living with invisible illness wants: a person who could very likely be exaggerating or appropriating symptoms for gain; a man who identifies as a victim diminished by injury and then goes scuba-diving and sits beaming like a prince on a Moroccan camel. As far as advocacy goes, it’s not the best look.Yet as someone who has, for nearly the past 20 years, lived with invisible illness, I can tell you that it is a legitimate look. My personal complex of illness stems from an unusual neurological condition called spontaneous cerebrospinal fluid leak syndrome, which leads to a brain with an insufficient cushion around it. I also have post-concussion syndrome. In my own decades with sickness as a varyingly close companion, there have been many points at which my life was truly defined by pain and disability on the inside, but still looked pretty nice and zippy on paper (or Facebook). I had two kids, I moved cities, I traveled, I hosted events, I wrote books and articles, I got out of a marriage that wasn’t working, I had boyfriends. Sometimes I did some of these things very slowly, as if from the middle of a lake of glue. Sometimes I did them white-knuckled, with a brain that felt like a fat, broiling whale bladder. Other times I was more fine — like now — and if someone were to encounter me on the street, they might assume I was 100 percent cured.What I am describing here is the between-space spectrum of functional illness, a zone occupied by many with invisible illnesses — with feet both in the world of the well and in the universe of the sick. The sociologist Arthur W. Frank has called this cohort “remission society.” But I prefer to think of it as a society of walking wounded, because the term better includes people affected by illnesses including lupus, Lyme disease, migraine, endometriosis and, yes, the stubborn remnants of concussion — all of which are more chronically pooh-poohed, disbelieved or gaslighted, not least by the medical community.Oddly, it’s a realm Paltrow says she herself inhabits. Just a few days before the trial began, the actor and Goop founder was lambasted for a podcast interview in which she seemed to suggest that her normal daily food intake was composed of coffee, bone broth and vegetables — a therapeutic diet she says has been helping her get over her own symptoms of long Covid and other health issues. (Paltrow later clarified that she eats “full meals.”) But the interview, which might have been strategically given to position Paltrow as a sick person who got uncomplainingly ill and then took care of her own business through an anti-inflammatory diet and a stiff upper lip (rather than blame and the courts), backfired: ​Not only did it make Paltrow look disordered and out of touch; it also put her own health issues into the same quotation marks as Sanderson’s. An illness invisible, and thus relentlessly questioned.So, I don’t believe that Sanderson is a victim of reckless Hollywood royalty on skis. But I do believe his brain injury. Because I know, intimately, what a brain injury can do. And I know that between illness and health, there really is no zero-​sum game. A man can have a life forever altered by a concussion. And he can also Zumba.Source photographs: mbbirdy/E+/Getty Images; screen grab from YouTube.