His regime is responsible for atrocities against the Syrian people.
For instance:
They were torturing to kill: inside Syrias death machine
For two years, between 2011 and 2013, the former Syrian military photographer known only as Caesar used a police computer in Damascus to copy thousands of photographs of detainees who were tortured to death in Bashar al-Assads jails. The media have run numerous stories about the man who managed to smuggle astonishing evidence of crimes against humanity out of the country at great risk to himself and his family but he had never been interviewed.
Month after month, for two years, this man, who has remained anonymous, took photographs of tortured, starved and burnt bodies. His orders were to photograph the bodies in order to document prisoners deaths. He then secretly made copies and transferred them on to USB keys so that he could smuggle them out of his office, hidden in his shoes or his belt, and pass them to a friend who could get them out of the country.
http://www.theguardian.com/world/2015/oct/01/they-were-torturing-to-kill-inside-syrias-death-machine-caesar
And also:
100,000 civilians killed by Assad forces since 2011: report
More than 133,000 people were killed, the majority of which civilians, in attacks by forces loyal to Syrian President Bashar al-Assad against areas held by opposition forces since the beginning of the conflict in March 2011, according to a London-based rights group.
The Syrian government forces killed no less than 133,586 people; including 109,347 civilian (88% of the total) among them 15,149 children and 13,695 women. In addition, 4892 person were killed under torture, said the latest report of the Syrian Network for Human Rights (SNHR).
"The majority of those killed (in the conflict) were civilians and most of them were killed as a result of indiscriminate regime shelling," Fadel Abdulghani, director of SNHR, told MEE.
"The figures show that the regime's barrel bombs and scud missiles have been the main cause of civilian deaths in the Syrian conflict," he added.
In SNHR's report, one child was killed every two hours, one woman was killed every three hours and around 100 people were killed every day in Syria by pro-Assad forces
http://www.middleeasteye.net/news/100000-civilians-killed-assad-forces-2011-report-590203858#sthash.l675azCh.dpuf