Han served as a principal deputy when Yoon held senior positions in the Supreme Prosecutors' Office of Korea.

He led the arrest of former President Lee Myung-bak by revealing that he was the real owner of auto parts maker "DAS" and investigated former Chief Justice Yang Sung-tae's alleged abuse of judicial administrative power and handed over a large number of former and current high-ranking judges to trial.

[6] In 2019, he was promoted to the chief prosecutor and led the investigation of the family of the Minister of Justice Cho Kuk as the head of the anti-corruption and power department, even though he was widely regarded as corrupt and immoral.

In June 2021,[7] due to the Ministry of Justice's personnel reshuffle with the prosecution, he was demoted again to the vice president of the Judicial Research and Training Institute.

[6] In his first speech as Justice Minister, Han stated that he would revive the Seoul Southern District Prosecutors Office's Joint Securities Crime Division (증권범죄합수단) that was abolished by his predecessor Choo Mi-ae.

[14] Despite his history as Minister of Justice in Yoon Suk Yeol cabinet, media reports often highlighted the 'conflict' between Han as ruling party leader and the government.

[20] Kim Kyung-yul, another major figure who was appointed to the emergency committee by Han and criticized the first lady, announced that he would not run in 2024 election.

[25][26] As the election period neared its end, he focused on highlighting the controversies of some candidates from DPK, including Yang Moon-seok and Kim Jun-hyuk.