Upul was called to the bar in 1976 and consequently served The Attorney General’s Department and was seconded as the First Legal Advisor of the Board of Investments. He was elected the Secretary to the Bar Association of Sri Lanka for the period 1991 – 1993. And later was Elected President of the Colombo Law Society in 2008.
Upul has appeared in many landmark cases including the Presidential Election Petition challenging the election of President Rajapaksha in 2010, appearing for the Presidential Candidate General Sarath Fonseka and many important Commercial matters.
He was elected the President of the Bar Association of Sri Lanka with the highest ever Majority in the history of the Bar Association Elections.
As the president of the BASL he championed Rule of Law and appeared in matters to establish Rule of Law.
Upul has stood against injustice and has been committed to protect the rule of law and the dignity of the profession and democratic values in Sri Lanka amidst serious threat. He played a major role in opposing the illegal impeachment of the then Chief Justice Dr Shirani Bandaranayake in the year 2013/2014. Consequent to the initiative against the impeachment, threats have been made on Upul’s life by unidentified gunmen.
He was persistent in the struggle against the illegal impeachment and was successful in having Her Ladyship the Chief Justice reinstated as the sitting Chief Justice in January 2015.
In 2015 he was appointed the Chairman of the Board of Investment of Sri Lanka, the premier statutory agency for investments.
Upul was awarded the 2nd CLA award on Rule of Law in Glasgow in 2015 and a cash award of US$ 5000 which he presented to the wife of a slain Journalist Mrs Sandya Ekneligoda.
Apart from his commercial legal practice, he is also heavily involved in public interest litigation. Most recently he appeared in the Supreme Court of Sri Lanka challenging the postponement of the Local Government Elections, and was successful in obtaining a stay order against the incumbent Minister of Finance, who is also the President of the Country, and the Secretary to the Treasury compelling them to fund the Local Government Elections. The said order irked the ruling party and the President which lead to a proposal being entertained by the Speaker of Parliament to summon the 3 Judges of the Apex Court who issued the said Order before the Privileges Committee of the Parliament. This move has been opposed by many esteemed local and international legal bodies including the CLA.
He has also challenged the Former President Gotabhaya Rajapakshe, his two brothers Mahinda and Basil Rajapakshe successive Ministers of Finance, the entire Cabinet of Ministers, the Monetary Board of the Central Bank of Sri Lanka and two successive Governors of the Central Bank of Sri Lanka relating to the crash of the Sri Lankan economy. This case has been heard before a Divisional Bench of five judges in the Supreme Court of Sri Lanka chaired by the Chief Justice. This matter was heard on 24 days and has now been reserved for judgments.