Some links on this page are affiliate links: if you buy through them we may earn a commission, at no extra cost to you.
Masimo did sue U.S. Customs and Border Protection (CBP) over Apple’s return of Blood Oxygen to Apple Watches in the United States—but the challenge did not ultimately restore the original feature ban. Masimo’s August 2025 lawsuit targeted CBP’s approval of Apple’s redesigned, phone-assisted system. The International Trade Commission (ITC) later cleared that redesign, and Masimo agreed to drop the CBP case in April 2026.
The short version
This was not simply another patent lawsuit in which Masimo sued Apple. Masimo sued CBP and federal officials in the U.S. District Court for the District of Columbia, arguing that the agency had unlawfully allowed redesigned Apple Watches into the country.
The dispute involved two different Apple Watch implementations:
Quick wins for a faster PC:
Repair Windows errors before they cause bigger problemsFix Now →Scan for outdated or missing drivers - takes under a minuteDriver Scan →Clear out junk files and repair common Windows errorsFree Scan →- Original implementation: the watch performed the blood-oxygen functionality that the ITC found infringed Masimo-related patents.
- Later redesign: the watch collected sensor information, while a paired iPhone performed the final blood-oxygen calculation.
CBP concluded that the redesigned watch, considered by itself at importation, did not directly infringe the relevant patent claims. The ITC subsequently examined the redesign in its own enforcement and modification proceeding and ultimately cleared it. That is why the later return of Blood Oxygen was not a reversal of the original ITC ruling.
#1 Best Overall
![Apple Watch Series 11 [GPS 46mm] Smartwatch with Jet Black Aluminum Case with Black Sport Band - M/L. Sleep Score, Fitness Tracker, Health Monitoring, Always-On Display, Water Resistant](https://m.media-amazon.com/images/I/416RQ0rtsUL._SL160_.jpg)
- A FULL-FEATURED HEALTH TRACKER—Apple Watch Series 11 gives you invaluable insights about your body, right from your wrist. Take an ECG anytime* and get alerts for a high and low heart rate or an irregular rhythm*—so you can stay closer to your heart. You can also view your overnight health tracking metrics with the Vitals app* and be notified of possible sleep apnea.*
- KNOW YOUR SLEEP SCORE—With advanced sleep tracking, Series 11 gives you a daily sleep score. It’s an easy way to help measure and understand the quality of your sleep, so you can make it more restorative.
- GET HYPERTENSION NOTIFICATIONS—Did you know that Series 11 can spot signs of chronic high blood pressure? By analyzing how your blood vessels respond to beats of the heart, it can notify you of possible hypertension.*
- SAFETY FEATURES—A smartwatch that puts your safety first. Series 11 can detect a hard fall or severe car crash, automatically help connect you with emergency services, and notify your emergency contacts.* Check In can automatically notify a loved one when you’ve arrived at your destination.
- A POWERFUL FITNESS TRACKER—With advanced metrics and motivating features like Pacer, Heart Rate Zones, training load, and Workout Buddy powered by Apple Intelligence from your nearby iPhone*—Series 11 is made to help everyone stay active, from runners and hikers to strength-training enthusiasts.
Why Apple Watch Blood Oxygen disappeared in the U.S.
Apple introduced Blood Oxygen with the Apple Watch Series 6 in 2020. Masimo and Cercacor later accused Apple of infringing patents related to wearable pulse-oximetry technology.
The ITC found that Apple violated Section 337 and issued a limited exclusion order covering infringing Apple Watches. The order led Apple to halt U.S. sales of affected models with Blood Oxygen enabled. The Apple Watch Series 9 and Apple Watch Ultra 2 were the models most closely associated with the U.S. sales disruption, although the underlying litigation had a broader technical and procedural history.
Apple sold versions with the feature disabled while pursuing legal and engineering alternatives. The dispute was therefore about more than whether a sensor physically existed inside the watch: it also concerned how the system performed the patented steps.
Rank #2
![Apple Watch Series 11 [GPS 42mm] Smartwatch with Rose Gold Aluminum Case with Light Blush Sport Band - S/M. Sleep Score, Fitness Tracker, Health Monitoring, Always-On Display, Water Resistant](https://m.media-amazon.com/images/I/31caPPnRysL._SL160_.jpg)
- A FULL-FEATURED HEALTH TRACKER—Apple Watch Series 11 gives you invaluable insights about your body, right from your wrist. Take an ECG anytime* and get alerts for a high and low heart rate or an irregular rhythm*—so you can stay closer to your heart. You can also view your overnight health tracking metrics with the Vitals app* and be notified of possible sleep apnea.*
- KNOW YOUR SLEEP SCORE—With advanced sleep tracking, Series 11 gives you a daily sleep score. It’s an easy way to help measure and understand the quality of your sleep, so you can make it more restorative.
- GET HYPERTENSION NOTIFICATIONS—Did you know that Series 11 can spot signs of chronic high blood pressure? By analyzing how your blood vessels respond to beats of the heart, it can notify you of possible hypertension.*
- SAFETY FEATURES—A smartwatch that puts your safety first. Series 11 can detect a hard fall or severe car crash, automatically help connect you with emergency services, and notify your emergency contacts.* Check In can automatically notify a loved one when you’ve arrived at your destination.
- A POWERFUL FITNESS TRACKER—With advanced metrics and motivating features like Pacer, Heart Rate Zones, training load, and Workout Buddy powered by Apple Intelligence from your nearby iPhone*—Series 11 is made to help everyone stay active, from runners and hikers to strength-training enthusiasts.
How Apple’s workaround worked
Apple did not necessarily remove the optical sensor hardware. In the later design-around, the watch continued to gather relevant information, but the paired iPhone handled the final blood-oxygen calculation.
Apple’s legal theory was that the watch alone, at the time it entered the United States, did not perform the complete combination of steps covered by Masimo’s patent claims. Apple announced the U.S. return of Blood Oxygen on August 14, 2025, saying that CBP had approved the redesigned implementation. See Apple’s announcement.
This distinction matters. Describing the change as “Apple removed the blood-oxygen sensor” is too simple. The central issue was the architecture and location of the processing, along with whether the imported watch fell within the ITC’s exclusion order.
Rank #3
![Apple Watch SE 3 [GPS 40mm] Smartwatch with Starlight Aluminum Case with Starlight Sport Band - S/M. Fitness and Sleep Trackers, Heart Rate Monitor, Always-On Display, Water Resistant](https://m.media-amazon.com/images/I/31YiTby0pOL._SL160_.jpg)
- GET SMARTER HEALTH INSIGHTS—Apple Watch SE 3 is an advanced health tracker that helps you better understand your body. The smartwatch sends alerts for an irregular heart rhythm, or an unusually high or low heart rate.* You can view your overnight health tracking metrics with the Vitals app,* track your sleep score, and get sleep apnea notifications.*
- A GREAT FITNESS TRACKER—SE 3 can track your workouts in a healthy number of ways—from running and strength training to simply achieving your 10K steps a day. With real-time metrics and Workout Buddy powered by Apple Intelligence from your nearby iPhone,* you’ll hit your goals like never before.
- KEEP HELP CLOSE AT HAND—SE 3 is a smartwatch that can detect a hard fall or severe car crash and automatically help connect you to emergency services and notify your emergency contacts.* Check In can automatically notify a loved one when you’ve arrived at your destination.
- WOMEN’S HEALTH INSIGHTS—SE 3 has advanced sensors that track your wrist temperature while you sleep. With this smartwatch, you can log your periods and symptoms, get period predictions, and get notified of cycle deviations.*
- GREAT BATTERY LIFE AND FASTER CHARGING—Enjoy a smartwatch with all-day, 18-hour battery life* from sunup to sundown. Then charge up to twice as fast as SE 2* and get up to 8 hours of battery in just 15 minutes.*
Why CBP—not only Apple or the courts—was involved
The agencies and courts had different roles:
- ITC: issued the Section 337 exclusion order against infringing imported products.
- CBP: administers exclusion orders at the border and evaluates whether a redesigned imported product falls within one.
- Federal courts: review particular legal disputes, including challenges to agency action and appeals from relevant decisions.
Masimo argued that CBP’s August 1, 2025 internal advice ruling, HQ H351038, effectively created a loophole that weakened the ITC order. But CBP did not conventionally “overturn” the ITC. It issued an import-enforcement ruling about the redesigned watch. The ITC later considered the same redesign through a separate proceeding.
What Masimo alleged in its lawsuit
Masimo filed Masimo Corp. v. U.S. Customs and Border Protection, No. 1:25-cv-02749, on August 20, 2025. Its complaint alleged that:
- CBP had reversed its earlier position without a material change in circumstances;
- Masimo did not receive meaningful notice or an opportunity to respond;
- Apple initiated an ex parte process that led to the ruling;
- CBP exceeded its authority under the Administrative Procedure Act; and
- the watch-and-iPhone combination effectively nullified the ITC’s exclusion order.
These were allegations in Masimo’s complaint, not findings that the court had already made. Masimo sought emergency relief, including a temporary restraining order and preliminary injunction, to block CBP’s decision.
Rank #4
![Apple Watch SE 3 [GPS 40mm] Smartwatch with Midnight Aluminum Case with Midnight Sport Band - S/M. Fitness and Sleep Trackers, Heart Rate Monitor, Always-On Display, Water Resistant](https://m.media-amazon.com/images/I/31Gq8SToFJL._SL160_.jpg)
- GET SMARTER HEALTH INSIGHTS—Apple Watch SE 3 is an advanced health tracker that helps you better understand your body. The smartwatch sends alerts for an irregular heart rhythm, or an unusually high or low heart rate.* You can view your overnight health tracking metrics with the Vitals app,* track your sleep score, and get sleep apnea notifications.*
- A GREAT FITNESS TRACKER—SE 3 can track your workouts in a healthy number of ways—from running and strength training to simply achieving your 10K steps a day. With real-time metrics and Workout Buddy powered by Apple Intelligence from your nearby iPhone,* you’ll hit your goals like never before.
- KEEP HELP CLOSE AT HAND—SE 3 is a smartwatch that can detect a hard fall or severe car crash and automatically help connect you to emergency services and notify your emergency contacts.* Check In can automatically notify a loved one when you’ve arrived at your destination.
- WOMEN’S HEALTH INSIGHTS—SE 3 has advanced sensors that track your wrist temperature while you sleep. With this smartwatch, you can log your periods and symptoms, get period predictions, and get notified of cycle deviations.*
- GREAT BATTERY LIFE AND FASTER CHARGING—Enjoy a smartwatch with all-day, 18-hour battery life* from sunup to sundown. Then charge up to twice as fast as SE 2* and get up to 8 hours of battery in just 15 minutes.*
The two-track timeline
| Date | What happened |
|---|---|
| 2020 | Apple introduced Blood Oxygen on Apple Watch Series 6. |
| August 1, 2025 | CBP issued ruling HQ H351038 concerning Apple’s second redesign. |
| August 14, 2025 | Apple announced that Blood Oxygen would return to U.S. Apple Watches through a phone-assisted implementation. |
| August 20, 2025 | Masimo sued CBP in the District of Columbia. |
| November 14, 2025 | The ITC opened a combined enforcement and modification proceeding concerning the redesign. |
| January 28, 2026 | The ITC administrative-law judge held an evidentiary hearing. |
| March 18, 2026 | The administrative-law judge issued an initial determination finding that the redesigned products did not infringe the asserted Masimo patents. |
| March 19, 2026 | The Federal Circuit affirmed the original ITC determination against Apple. |
| April 17, 2026 | The ITC issued its final enforcement determination clearing the redesigned implementation. |
| April 28, 2026 | Bloomberg Law reported that Masimo agreed to drop the CBP lawsuit. |
The key is not to merge the March 18 and March 19 decisions. The administrative-law judge’s finding concerned Apple’s later redesign. The Federal Circuit’s ruling concerned the original ITC determination and exclusion order.
Independent reader supportYour contribution helps us test, update, and keep practical guides available for everyone.What happened to the CBP case?
The later ITC proceeding changed the practical importance of Masimo’s district-court challenge. Once the ITC separately cleared the redesign, an injunction against CBP would have been far less useful as a way to keep that implementation out of the United States.
Free tools Windows power users keep installed
One-click scans. No signup required.
Masimo subsequently agreed to drop the CBP action, according to Bloomberg Law and disclosures described in Masimo’s SEC filing.
Best Value
![Apple Watch Series 11 [GPS 42mm] Smartwatch with Jet Black Aluminum Case with Black Sport Band - S/M. Sleep Score, Fitness Tracker, Health Monitoring, Always-On Display, Water Resistant](https://m.media-amazon.com/images/I/41s72HIk5TL._SL160_.jpg)
- A FULL-FEATURED HEALTH TRACKER—Apple Watch Series 11 gives you invaluable insights about your body, right from your wrist. Take an ECG anytime* and get alerts for a high and low heart rate or an irregular rhythm*—so you can stay closer to your heart. You can also view your overnight health tracking metrics with the Vitals app* and be notified of possible sleep apnea.*
- KNOW YOUR SLEEP SCORE—With advanced sleep tracking, Series 11 gives you a daily sleep score. It’s an easy way to help measure and understand the quality of your sleep, so you can make it more restorative.
- GET HYPERTENSION NOTIFICATIONS—Did you know that Series 11 can spot signs of chronic high blood pressure? By analyzing how your blood vessels respond to beats of the heart, it can notify you of possible hypertension.*
- SAFETY FEATURES—A smartwatch that puts your safety first. Series 11 can detect a hard fall or severe car crash, automatically help connect you with emergency services, and notify your emergency contacts.* Check In can automatically notify a loved one when you’ve arrived at your destination.
- A POWERFUL FITNESS TRACKER—With advanced metrics and motivating features like Pacer, Heart Rate Zones, training load, and Workout Buddy powered by Apple Intelligence from your nearby iPhone*—Series 11 is made to help everyone stay active, from runners and hikers to strength-training enthusiasts.
As of August 18, 2026, the accurate summary is: the original Apple Watch implementation remained subject to the affirmed exclusion order, while the later watch-plus-iPhone redesign was cleared in the separate ITC proceeding. The CBP lawsuit did not decide every Apple-Masimo dispute, including any separate patent, trade-secret, damages, or patent-office matters.
What this means for Apple Watch owners
For buyers and existing owners, the legal history has several practical implications:
- Check the market and model. Blood Oxygen availability can depend on the Apple Watch model, sales region, and purchase date.
- Expect iPhone involvement. In the U.S. redesign described here, the watch’s sensor data and the iPhone’s calculation are part of the system. A compatible paired iPhone and current software may be required.
- Do not assume every model behaves identically. Confirm Apple’s current support information for the exact watch, iPhone, and region before buying.
- Understand the wellness limitation. Blood Oxygen is a consumer wellness feature, not a substitute for a medical-grade diagnostic device, clinical pulse oximeter, or professional medical advice.
- Recognize that availability can change. This dispute shows that a health feature may be disabled, redesigned, or restricted by legal and regulatory action. The later redesign’s ITC clearance reduced the immediate risk described in this case but does not guarantee identical availability in every market or future product.
Apple Watch versus a dedicated pulse oximeter
The lawsuit does not establish that Apple Watch readings are medically equivalent to Masimo’s clinical products—or that one brand is generally more accurate.
Windows Errors? Fix Them Before They Spread
Repair common Windows errors and clear accumulated junk for a smoother, more stable PC - no reinstall needed.Free scan · no reinstallOutdated Drivers Are Slowing You Down
One free scan finds every outdated or missing driver and matches the right update for your exact hardware.Free scan · exact hardware matchA buyer comparing products should check:
- whether the product is regulated as a medical device;
- its intended use: general wellness, monitoring, or diagnosis;
- whether calculations occur on the device or through a phone;
- availability in the buyer’s country;
- performance limitations involving motion, cold extremities, low perfusion, darker skin tones, or nail polish;
- FDA clearance or other applicable authorization for the specific use; and
- data storage, privacy, and interoperability.
Apple’s wellness feature and Masimo’s clinical or professional products occupy different regulatory and use-case categories. They should not be treated as interchangeable without product-specific evidence and authorization.
The bottom line on the lawsuit
Masimo challenged CBP because it believed the agency had improperly allowed Apple to import a redesigned Apple Watch capable of participating in Blood Oxygen measurements with an iPhone. CBP’s ruling was about import enforcement, not a final universal patent judgment. The original ITC exclusion order was later affirmed by the Federal Circuit, but the ITC separately cleared Apple’s redesign. Masimo then agreed to drop the CBP case, leaving U.S. Blood Oxygen availability tied to the later implementation rather than the original one.
Quick Recap
Sources
- CBP ruling HQ H351038
- Masimo complaint
- Federal Circuit opinion
- Masimo SEC filing
- District-court docket
Product prices and availability are accurate as of the date/time indicated and are subject to change. Any price and availability information displayed on Amazon at the time of purchase will apply.
