In some situations, Virginia law permits officers to make an arrest in Virginia without having obtained an arrest warrant, and in other situations Virginia law prohibits doing so. The law in Virginia regarding the circumstances under which law enforcement officers can lawfully effect an arrest without having an arrest warrant in hand is a bit complicated.
In order to comply with the United States Constitution, all arrests require an officer to have probable cause to believe a specific person committed a specific offense. Assuming an officer has the required probable cause, Virginia law allows officers to arrest for felony offenses even though an arrest warrant has not yet been obtained. Felony offenses are more serious offenses and it makes sense to allow officers to go ahead and make an arrest, rather than having to take the time to go get a warrant and then return to make the arrest.
However, the rules are different in Virginia for misdemeanor offenses. As a general rule, officers in Virginia are not permitted to make arrests for misdemeanor offenses which did not occur in their presence. However, whenever you see the term "general rule" it indicates there are exceptions to that rule, and the same is true here. There are certain situations in which Virginia law allows officers to make an arrest for misdemeanor offenses, without first obtaining an arrest warrant, even though the offense did not occur in the officer's presence. Although there are more, a few of those misdemeanor offenses are: driving under the influence (DUI / DWI), boating under the influence, shoplifting, carrying a prohibited weapon on school property, assault and battery, and brandishing a firearm.