First Degree Murder?
When Sonny is arrested at his Church, he's charged with first degree murder (i.e. premeditated murder).
The circumstances of the baseball scene make it obvious that there was no premeditated murder involved, in fact there probably wasn't even an intent to kill. Realistically, the most I could see him being convicted of is manslaughter (possibly voluntary if the judge wants to stick it to him, otherwise involuntary).