President Obama arrives Sunday in Paris to finalize a global climate-change pact that if completed would be a legacy-defining part of his presidency. But he awaits challenges at home and abroad, including questions about who will pay for the changes and whether terrorism is a more imminent concern.
Messy legal process could challenge Trump's mass deportation plan
On Their Trail
FBI using elite surveillance teams to track at least 48 high-risk ISIS suspects
The Damage Done
Heroin epidemic seizes bipartisan attention in 2016 race
'Unfair Sales Act'
Black Friday blackout: The state where below-cost prices are illegal