Why did John Locke think the state of nature could still lead to injustice and violence?

In John Locke’s political theory, the state of nature is a condition of freedom and equality governed by the law of nature, which dictates that no one ought to harm another in their life, liberty, or possessions.123

However, Locke argued that this state can still lead to injustice and violence because every individual possesses the natural right to enforce the law of nature and punish offenders. When the authority to judge and punish is placed in the hands of each person, it creates a situation where individuals may act as biased judges in their own cases. This lack of an impartial, common authority to arbitrate disputes and redress injuries makes it difficult to guarantee the protection of rights and the enforcement of agreements.1324

To remedy these inconveniences, Locke proposed that individuals enter into a social contract to establish a civil society and a government. This institution provides the necessary impartial power to enforce the law of nature and ensure that justice is maintained consistently for all citizens.143