A line of Apple Watches on display, some showing the front and some showing backs.

A new class action lawsuit claims the Apple Watch's blood oxygen sensor isn't formatted to take darker skin tones into account, which is only compounding the biases of blood sensor tech that has failed to accurately gauge blood oxygen levels for black and brown people.

According to court documents, the suit was filed on behalf of a New York resident who purchased an Apple Watch between 2020 and 2021. 21 days is the amount of time Apple has to respond to the summons.

Light can be used to register oxygen saturation. There are simpler, light-based oximeters that can be used on phones and smart watches. The medical community is aware of the inherent bias shown by pulse oximeters on darker skin tones. Researchers are trying to develop oxygen readers that work on darker skin tones.

Since the Series 6 Apple Watches have had the Blood Oxygen feature. The company says it compensates for natural variations in the skin by using four clusters of light on the back of the watch. The Blood Oxygen app page states that the measurement are not intended for medical use. Although the lawsuit doesn't explicitly say Morales or other users utilize Apple Watches to gauge accurate medical data, it does propose that Apple has failed "to recognize the failings of pulse oximetry in general with respect to persons of color." Researchers have confirmed the clinical significance of racial bias of pulse oximetry using records of patients taken during and before the Pandemic.

We didn't hear back from Apple after we contacted them.

Studies show that minorities and other marginalized groups were hurt worse during the worst months of the covid epidemic. Two years ago a letter was published in The New England Journal of Medicine stating that pulse oximetry devices were failing to accurately gauge when black patients entered a state of hypoxemia.

The lawsuit states that the real world significance of this bias was not addressed until the middle of the coronaviruses epidemic.

Users complained about dark tattoos messing with the device's sensors in 2015. There is no mention of skin color in the Apple Blood Oxygen app page.

There is no concrete example of a user getting inaccurate results from the blood sensor. We will update this story if we hear back from the law firm. The lawsuit references a study published in the Digital Health open access journal that claimed Apple's oxygen sensor was on par with most medical-grade oximetry devices.

This latest in a long line of user deception claims shows what happens when companies cram "everything" devices full to the brim with technology, even tech that has proved racially biased. The ability to capture dark skin accurately has been explicitly marketed by companies like Google in the past. Some users have reported issues with the dark skin tone rendering even with the latest versions of the device.

The suit is welcoming claims from New York as well as North Dakota, Wyoming, Idaho, Alaska, Iowa, Mississippi, and Arkansas.