The trials of Kyle Rittenhouse and three men accused of killing Ahmaud Arbery had vastly different outcomes. But coming just days apart, they laid bare a dangerous and long-running current in the fight for racial equality: The move by some white Americans to grab guns and take their own stand against perceptions of lawlessness, particularly by Black people.

The two cases, which ended with an acquittal for Rittenhouse last week and a guilty verdict for Arbery's killers on Wednesday, highlighted polarizing issues about gun and self-defense laws, and racial injustice.

They also forced the questio...