United States Senator Mark Kelly has sued the Department of Defense and its secretary, Pete Hegseth, over allegations they trampled his rights to free speech by embarking on a campaign of “punitive retribution”.The complaint was filed on Monday in the US district court in Washington, DC. It also names the Department of the Navy and its secretary, John Phelan, as defendants.Recommended Stories list of 3 itemsend of list“I filed a lawsuit against the Secretary of Defense because there are few things as important as standing up for the rights of the very Americans who fought to defend our freedoms,” Kelly, a veteran, wrote in a statement on social media.Kelly’s lawsuit is the latest escalation in a feud that first erupted in November, when a group of six Democratic lawmakers – all veterans of the US armed services or its intelligence community – published a video online reminding military members of their responsibility to “refuse illegal orders”.Democrats framed the video as a simple reiteration of government policy: Courts have repeatedly ruled that service members do indeed have a duty to reject orders they know to violate US law or the Constitution.But Republican President Donald Trump and his allies have denounced the video as “seditious behaviour” and called for the lawmakers to face punishment.A focus on KellyKelly, in particular, has faced a series of actions that critics describe as an unconstitutional attack on his First Amendment right to free speech.A senator from the pivotal swing state of Arizona, Kelly is one of the highest-profile lawmakers featu …