President Trump may have acted within the law Wednesday in criticizing Nordstrom on Twitter, but at least one ethics expert saw the outburst as an abuse of power that could cause headaches for the administration in the future.

Trump on Wednesday morning criticized the retailer’s decision to drop his daughter Ivanka Trump’s clothing line, calling it “terrible.” That tweet was retweeted by the official @POTUS account maintained by the White House, and Trump’s criticism was later defended by White House Press Secretary Sean Spicer, who said that Trump has the right to stand up for his family.