President Barack Obama's commutation of the sentence of Oscar López Rivera, who was convicted for his role in a Puerto Rican nationalist group linked to bombings in US cities, ends a decades-long fight to free a man who supporters call a "political prisoner." López Rivera, who was serving more than 50 years in prison for plotting to overthrow the US government, belonged to Armed Forces of National Liberation, known by its Spanish acronym FALN. López Rivera wasn't charged directly in FALN's attacks but more broadly with charges of plotting to overthrow the US government. His prison sentence was expected to expire in 2051, but he will walk free on May 17, 2017. Obama's commutation reduces the sentence being served, but it does not change a conviction, whereas a pardon forgives a certain criminal offense.