Senator Markey's call for the 25th Amendment has sparked social media debate over Trump's letter to Norway's PM. Here's what it means.

How could a sitting US president be legally removed from office? Most people have heard of impeachment, a power granted to (and rarely used by) the US Congress. But there’s also the 25th amendment to the US Constitution,

The 25th Amendment explained as debate resurfaces following Donald Trump's 33 posts in 45 minutes and renewed attention on presidential capacity.