I’m in the middle of a series of posts related to the case of James Fields, Jr., who drove his car into a crowd of counterprotestors in Charlottesville, Virginia, killing one person and injuring others. He was originally charged with second degree murder, but the charges have been upgraded to first degree.

So what’s the difference between first and second degree murder?

Both crimes involve the same act: taking a human life. What differentiates them (and all other forms of homicide) is the defendant’s mental state. For second degree, the defendant must intentionally kill. For first degree, he must kill intentionally and with premeditation. In other words, second degree might be a split second decision, but first degree requires some amount of forethought. Because we believe that a planned murder is more blameworthy, first degree carries a more serious penalty than second.

Now, when I say “premeditation,” you may be picturing a villain spending months scheming away, developing the perfect plan to do away with her nemesis. That would certainly count. But the law doesn’t actually require that much. In fact, the defendant might ponder for only seconds before she acts. Or if the killing takes some time—such as when the victim is strangled, for example—the pondering might even take place during the act itself. All that’s required is proof that the defendant had time and opportunity to think about what she was doing to the victim.

It’s also worth noting that the defendant doesn’t have to develop intent to kill any particular person. It’s enough if he decides to create substantial risk to human life in general—such as shooting into a passenger train, setting up a bomb in a public place, placing poison in something people are likely to consume, or dropping a heavy object off an overpass onto a highway.

In Fields’s case, videos show the defendant driving slowly toward the crowd, backing up and then accelerating directly into numerous people. He then quickly reversed again, striking more people before getting away. The prosecutor will have to prove that in those short moments before his foot hit the gas, Fields deliberately decided to strike people with with his vehicle at a substantial speed. If the prosecutor can prove that, Fields may end up convicted of first degree murder.

Next week: What if the prosecutor can’t prove premeditation?

On August 12, 2017, a group of people were in the streets of Charlottesville, Virginia, counterprotesting white nationalists. James Fields, Jr., a man with a reported fascination for Nazis, apparently deliberately drove his car into a crowd. He killed one person, Heather Heyer, and injured dozens more. Just last week, prosecutors announced they’d be seeking a first degree murder conviction against him. For the next few weeks, I’ll be posting on some issues related to this case.

Today I’m going to talk about how criminal charges might evolve in a case.

In a typical criminal case, a person is arrested by police. The police report will list at least one potential criminal violation; police are supposed to have probable cause to believe that the suspect has committed this crime.

The prosecutor will review the report and decide whether to pursue the case (incidentally, this is one reason why police must have decent writing skills). If the prosecutor opts to go forward, she’ll issue something called a criminal complaint. This will specify the parts of the criminal code which the defendant is alleged to have violated. These charges may or may not be the same crimes named in the arrest report because the prosecutor may find that fewer, additional, or different offenses are better substantiated.

Within a short period of time—usually two business days—the defendant will be arraigned. As part of this process, he’ll be informed of the charges in the complaint.

In Fields’s case, the complaint charged him with second degree murder along with a slew of lesser offenses such as malicious wounding.

After the arraignment, the prosecutor will conduct additional investigations (as will the defense attorney). Eventually there will be a probable cause hearing, the purpose of which is to determine whether there’s sufficient evidence to proceed with the case. That hearing may be a preliminary hearing, in front of a judge, or it may be a grand jury proceeding, in front of a group of citizens. In either case, the prosecutor has to produce enough evidence for the charges to stick. And sometimes, perhaps pursuant to additional evidence that’s been collected, those charges may be different from those in the complaint.

That’s what’s happened in Fields’s case. The preliminary hearing was last week, and the prosecutor opted to upgrade the most serious charge from second to first degree murder. The judge found enough evidence to support first degree, so that’s the charge Fields now faces.

In some cases, charges may continue to evolve after the probable cause hearing. Prosecutors may drop some charges or, pursuant to a plea bargain, defendants might plead guilty to a lesser offense.

Next week: the difference between first and second degree murder.