The moment lasted about 20 seconds. But its political reverberations have endured for a year and exemplify today's knotty confluence of law, politics and public perception.

At last year's State of the Union speech Jan. 27, with six Supreme Court justices in attendance, President Obama denounced a recent campaign-finance ruling, saying it reversed a century of precedent and warning that it would "open the floodgates" for corporate spending on elections. Justice Samuel Alito shook his head and mouthed "not true."

That tense moment has been viewed on youtube.com more than 650,000 times in the past year. It was singularly controversial but not the only headline-grabbing interaction between members of the political branches and the Supreme Court in the past twelve months.

A series of events, most recently Justice Antonin Scalia's acceptance of an invitation to speak to Tea Party members, has made clear that against the backdrop of an increasingly polarized Washington and the 24-hour media frenzy, interactions between justices and the two elected branches have become more politicized.