According to the papers filed by Apple, the Cupertino-based firm isn't best pleased about the way Samsung has implemented the Google Now feature on its latest flagship smartphone.
It's claiming the handset infringes on the some of the patents it holds for Siri, which it's already flagged up on other Samsung devices.
Foss Patents picked up a line in the firm's legal documentation which reads: "Apple determined that the Galaxy S4 product practices many of the same claims already asserted by Apple, and that the Galaxy S4 practices those claims in the same way as the already-accused Samsung devices."
There's some positive news for Samsung though, as Apple tried to challenge one of the patents in question - referring to Google's Android Quick Search Box - back in 2012 in relation to the Samsung Galaxy Nexus, but the judge in charge of the hearing overruled the Cupertino firm.
With a positive history already surrounding this particular area of the dispute Samsung has reason to feel pretty confident going into court, but you can be sure Apple's army of lawyers won't give up without a fight.
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John joined TechRadar over a decade ago as Staff Writer for Phones, and over the years has built up a vast knowledge of the tech industry. He's interviewed CEOs from some of the world's biggest tech firms, visited their HQs and has appeared on live TV and radio, including Sky News, BBC News, BBC World News, Al Jazeera, LBC and BBC Radio 4. Originally specializing in phones, tablets and wearables, John is now TechRadar's resident automotive expert, reviewing the latest and greatest EVs and PHEVs on the market. John also looks after the day-to-day running of the site.