Apple just reintroduced a blood-oxygen reading feature to some Apple Watches last week, but a new lawsuit could force the company to turn it off again.

Following a decision that offered Apple a way to bring its Apple Watch blood oxygen tool back in the U.S., Bloomberg reports that Masimo alleges U.S. Customs and Border Protection "unlawfully let Apple Inc.

The feature was removed on select smartwatches due to a patent-infringement lawsuit, but Apple has “redesigned” it.