Possible answer:

The Sri Lankan Government has taken several steps to establish the supremacy of the law, which aims to ensure that all citizens are equal before the law and that no one is above it. These steps include:

1. Enacting laws: The Sri Lankan Parliament has passed several laws to strengthen the legal framework of the country and to prevent the abuse of power by the state and its agents. For example, the 19th Amendment to the Constitution has reduced the powers of the Executive Presidency and restored the independence of key institutions such as the judiciary, the police, and the election commission.

2. Strengthening institutions: The Sri Lankan Government has also taken measures to strengthen the capacity and integrity of key institutions that are responsible for upholding the rule of law, such as the judiciary, the police, and the Attorney General's Department. For example, it has appointed independent commissions to oversee the appointment, promotion, and disciplinary proceedings of public officials.

3. Addressing impunity: The Sri Lankan Government has initiated several investigations and prosecutions of alleged human rights violations and war crimes committed during the civil war, which lasted from 1983 to 2009. It has also established a Truth and Reconciliation Commission to address the grievances of victims and to promote reconciliation among communities.

4. Engaging with international partners: The Sri Lankan Government has engaged with international partners, such as the United Nations, the European Union, and the Commonwealth, to seek their support and advice in promoting the rule of law and human rights in the country. It has also ratified several international treaties and conventions that protect the rights of citizens and provide standards for good governance.

However, the long-lasting impact of these steps on establishing the supremacy of the law in Sri Lanka depends on several factors, such as:

1. Political will: The commitment of the Sri Lankan Government to upholding the rule of law and human rights must be sustained and not undermined by political expediency, partisan interests, or external pressures.

2. Implementation capacity: The ability of the Sri Lankan Government to implement the laws and policies that promote the rule of law and human rights must be strengthened, including by providing adequate resources, training, and accountability mechanisms.

3. Public awareness and participation: The Sri Lankan public must be aware of their rights and duties under the law and actively participate in the promotion and protection of the rule of law and human rights, including by reporting violations, seeking redress, and holding public officials accountable.

4. International support and scrutiny: The international community must continue to support and monitor the progress of Sri Lanka in promoting the rule of law and human rights, including by providing technical assistance, advocacy, and accountability mechanisms.

Therefore, while the steps taken by the Sri Lankan Government to establish the supremacy of the law are commendable, their long-lasting impact on the country's governance and human rights record will depend on a sustained and inclusive effort by all stakeholders.