With this floor sign, Senator Christopher Murphy (D-CT) has made himself a hero to emoticon fans everywhere.
He's also making a decent policy point about the policy stakes in the King v. Burwell litigation. The basic issue is that conservative activists have a lawsuit that, if successful, will strip millions of Americans of their Obamacare subsidies. Entire states' worth of health insurance exchanges will likely collapse, with dramatic consequences for people's lives. The Supreme Court could avoid this outcome by ruling for the government. And Congress could avoid this outcome by amending the Affordable Care Act. Democrats would embrace either of those ideas.
Republicans, by contrast, don’t want to disagree with conservative activists about the litigation but also don’t want to amend the law. Their basic stance is, for lack of a better word, ¯\_(ツ)_/¯.