The news: Walmart and its subsidiary Sam’s Club filed a suit against BJ’s Wholesale on Tuesday accusing the retailer of copying its patented mobile self-checkout technology, Scan & Go, per CNBC. The product in question is BJ’s Express Pay, which BJ’s introduced in late 2021.

Here’s how it works: Scan & Go launched in 2016 and lets customers purchase items in-store using the Sam’s Club app without having to stop at a checkout line. Customers scan product barcodes with their phones and pay directly in the app. They are then issued a digital receipt, which they show before leaving the store.

Why it’s worth watching: In-store payment innovations have increased as retailers search for ways to streamline in-store operations during the pandemic.

Kroger, for example, began testing Caper’s smart cart solution early last year, and Amazon’s Just Walk Out tech has landed in more stores. Walmart’s Scan & Go is one of the simpler technologies out there, so similar versions are likely to crop up as retailers look to keep up with growing demand for digital payments and simple in-store checkout.