Wednesday’s arrest of George Zimmerman, who has been charged with second-degree murder in the Trayvon Martin shooting, means that justice will run its course.

The decision by prosecutor Angela Corey to charge Zimmerman, 28, with this offense will provide an opportunity for all the facts to come out about this tragic case, which has dominated the national news in recent weeks and polarized many Americans.

It also should help citizens judge the value of the “Stand Your Ground” statute, which Zimmerman will use as the basis for his defense in a Florida courtroom. Georgia has a similar law. It gives people the right to defend themselves in public places if they fear for their safety.

Zimmerman, the self-appointed neighborhood watchman, shot Martin, an unarmed 17 year old, in a suburb of Orlando. He had been tailing the teenager and later shot the young man, apparently after an altercation ensued. But this case must not be about satisfying public opinion, which has all but convicted Zimmerman. It must be about finding the facts and following the law.

“We do not prosecute by public pressure or by petition,” Ms. Corey said. That’s encouraging. Many people, including President Obama, have expressed their opinions. Prosecutors must keep their professional blinders on.

Likewise, Zimmerman deserves his day in court. He’s innocent in the eyes of the law.

Ms. Corey wouldn’t say how she reconciled the conflicting accounts of what happened or explain how she arrived at the charges, which could put Zimmerman behind bars for life if he’s convicted. But she set the bar high.

To get a conviction for second-degree murder, she will have to show that the killing resulted from a “depraved” disregard for human life.

Much may depend on whether Zimmerman was the aggressor and went too far — even if he was physically attacked later. Credit Ms. Corey for filing charges, which should help provide answers.