There are certain rules that you are required to follow when you are in the company of the Queen of England, and being the President of the United States does not exempt you from the protocol.

Donald Trump sparked a debate on whether he had violated this protocol when he appeared to have brushed his hand against Queen Elizabeth’s shoulder. The president and his wife Melania Trump were attending a state banquet at Buckingham Palace during his visit to the UK when the incident took place. Trump finished his speech and seemed to put his hand on the Queen’s shoulder for a brief second when she stood up for a toast. You can watch the moment at the 11:40 mark in the video above.

According to the Evening Standard, traditional protocol dictates that in order to touch the Queen, she must first offer her hand to you. However, the website of the royal family does not list any such rule. Elizabeth herself appeared to be unfazed by the contact.

Trump is also not the first person to have broken the rule. Former first lady Michelle Obama also created controversy when she “laid a hand across her shoulder” in 2009.