Encryption is only effective when the phone is switched off. Therefore, practise how to switch off your phone quickly in stressful situations.
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Even if your phone is encrypted, professional mobile forensic software such as Cellebrite can access it via USB. Data could be extracted or spyware could be installed. As long as your phone is switched on, the encryption is ineffective as the data is decrypted. Encryption is only really effective when it is switched off. Your phone is then in the so-called 'Before First Unlock' status. It is extremely unlikely that unwanted access to the data can take place without the correct password, pattern or biometric feature.
So be sure to switch off your phone before you give it into someone else's hands! If you want to be on the safe side, you can also attach a killswitch to your phone. This allows you to quickly remove the battery in dangerous situations. You can find more details about this idea in the further information.