Back button behavior is correct for the platform

Broken back-button behavior is the most reliably reported UX defect in mobile app reviews. On Android, a hardware back press that skips a screen, crashes the app, or silently does nothing fails WCAG 2.2 SC 2.1.1 (Keyboard), which requires keyboard-equivalent navigation for all functionality. Beyond accessibility compliance, unexpected back behavior corrupts navigation state in ways that can strand users mid-flow — stranded on a checkout confirmation with no path to their cart, or dropped to an empty stack with no way to recover.

React Navigation handles the default back behavior automatically for most stack setups — only intervene when you need to intercept it (e.g., unsaved-form confirmation). Use useFocusEffect with BackHandler to manage the Android hardware back button on screens that need custom logic:

import { useFocusEffect } from '@react-navigation/native'
import { BackHandler, Alert } from 'react-native'

function EditFormScreen({ navigation }) {
  const [isDirty, setIsDirty] = React.useState(false)

  useFocusEffect(
    React.useCallback(() => {
      const onBackPress = () => {
        if (isDirty) {
          Alert.alert('Discard changes?', '', [
            { text: 'Cancel', onPress: () => null },
            { text: 'Discard', onPress: () => navigation.goBack() },
          ])
          return true // prevent default
        }
        return false // use default
      }

      BackHandler.addEventListener('hardwareBackPress', onBackPress)
      return () => BackHandler.removeEventListener('hardwareBackPress', onBackPress)
    }, [isDirty, navigation])
  )
}

For screens without custom needs, do not add a BackHandler at all — letting React Navigation's default behavior run is correct.