Mexico is one of the deadliest countries for journalism at a time when murder rates are at their highest since 2011.
"Mandatory minimum sentences have unfairly and disproportionately incarcerated too many minorities for too long," Paul said in a CNN op-ed.
The government's fight against criminal cartels accounted for 23,000 deaths in 2016.
The president has said he will accept investigators only if he gets to debate them, during which he would "humiliate" them and create a "spectacle."
"Here's the shocker: I will kill you. I will really kill you. And that's why the rapporteur of the U.N. is here, investigating extrajudicial killing," Duterte said.
The Homeland Security secretary says heroin, cocaine and meth are bigger problems.
The rights group claims Duterte's drugs war involves extrajudicial executions and falsified evidence.
The move will be a gesture of goodwill to a controversial figure, according to a Duterte aide.
Police will focus on arresting politicians, military, police, government officials and celebrities.
Those trying to stop the ivory trade can learn from people tackling drugs trafficking.
We live under the illusion that all problems can be dealt with through force.
Simple economics will be one of Colombia's biggest problems as it seeks to eliminate illegal drug production with the help of FARC rebels.
President Salvador Ceren has vowed to reduce the murder rate in one of the world's deadliest countries.
"I have a regret that the entire discussion about this article ignores its purpose," the actor said.
Joaquin Guzman was interviewed in a secret meeting by the actor Sean Penn in October. He was captured on Friday.