Infringement Analysis

In 2018, a jury ordered Samsung to pay Apple over $500 million for copying the design of the iPhone — rounded corners, a grid of icons, and a black rectangular front face. The case hinged on a single question that every intellectual property lawyer must learn to answer precisely: does this product infringe that patent, trademark, or copyright, and how do you prove it?

- The legal test for patent infringement (literal infringement vs. the doctrine of equivalents) - How copyright infringement analysis differs using the 'substantial similarity' test - Why trademark infringement hinges on 'likelihood of confusion,' not just similarity - How to apply claim construction to a real infringement scenario

Patent infringement analysis begins with claim construction — courts must first determine exactly what the patent's claims mean, word by word, often in a dedicated hearing called a Markman hearing (named after the 1996 Supreme Court case Markman v. Westview Instruments). Once claims are construed, a product infringes literally if it contains every single element listed in at least one claim. If even one element is missing, the analysis moves to the doctrine of equivalents: does the accused product perform substantially the same function, in substantially the same way, to achieve substantially the same result? This 'function-way-result' test, from Graver Tank & Mfg. Co. v. Linde Air Products (1950), prevents infringers from making trivial substitutions to dodge liability.

Copyright analysis works differently because copyright doesn't protect ideas, only their specific expression. Courts use a two-part test: first, did the defendant have access to the original work, and second, is there 'substantial similarity' between the protected expression in both works? In the famous 'Blurred Lines' case (Williams v. Gaye, 2015), Robin Thicke and Pharrell Williams were found to have infringed Marvin Gaye's 'Got to Give It Up' — not because they copied specific notes, but because a jury found the overall 'feel' and constellation of musical elements substantially similar. This case remains controversial because critics argue it blurred the line between protecting expression and protecting an unprotectable genre or style.

Trademark law protects consumers from confusion, not creators from competition — so the central test is 'likelihood of confusion,' evaluated through multi-factor tests like the Polaroid factors (from Polaroid Corp. v. Polarad Electronics, 1961). Courts weigh: similarity of the marks, similarity of the goods, evidence of actual confusion, the strength of the original mark, and the defendant's intent. This is why a small bakery named 'Delta Donuts' likely would not infringe Delta Air Lines' trademark — the goods are unrelated and confusion is unlikely — but a new airline calling itself 'Delta Express' almost certainly would.