The ugly fight raging between the main opposition Liberty Korea Party and the local police in the southeastern city of Ulsan exposes a negative aspect of the relationship between politics and law-enforcement authorities.

The controversy started when police investigators armed with a court-issued search and seizure warrant raided Ulsan City Hall on March 16 in connection with corruption and influence-peddling cases. They targeted the offices of the chief of staff to Mayor Kim Gi-hyeon and another senior city official.

What enraged the mayor and his party was that the police raid coincided with the party’s announcement that Kim was nominated to seek re-election in the June 13 local elections. Party officials believe the police chose the date to damage Kim’s re-election campaign.

Police denied the allegations, saying that the investigation was prompted by tip-offs and that they did not know about the nomination announcement.

There are some grounds to the party officials’ argument. The investigation targets eight people implicated in three cases, including the mayor’s two brothers. It will take a while before the court makes its final judgment on the cases, but the fact that associates and family members of the mayor were implicated in corruption cases itself could deal a heavy blow to Kim’s campaign.

The Liberty Korea Party is sensitive to the development because Ulsan and neighboring South Gyeongsang Province are part of the conservative opposition party’s traditional stronghold. Party officials fear that the ruling Democratic Party of President Moon Jae-in could make all-out efforts to break the Liberty Korea Party’s dominance in the region by taking advantage of Moon’s popularity.

While the wariness of the opposition party is understandable, the way it responded to the police investigation was hardly acceptable. Party spokesman Chang Je-won called the Ulsan police and its chief Hwang Un-ha a “mad dog” and a “hunting dog” working for the Moon government.

Party leader Hong Joon-pyo, a maverick already famous for his use of coarse language, joined the offensive, saying that only one eel was stirring up the mud in the ditch.

The attacks brought an immediate backlash from police officers across the country, with thousands joining the campaign to post their pictures with protest signs on the internet and social media.

In the face of the fierce protests, Chang offered apologies. But the party is not withdrawing altogether. Chang said that he wanted to criticize only some “politicized” police officers like Hwang who follow the government in power and that they must be ousted.

Party officials said they plan to take the case to the prosecution to ask for investigation on Hwang over suspected intervention in the election campaign.

The Ulsan case drew more public and political attention because it came at a time the Moon government and politicians are discussing reform of the criminal justice system, which is focused on realignment of the investigative powers of the prosecution and police.

The rationale for the reform was that the state prosecution, which has the authority to command police investigations and is the only agency with the right to seek warrants and indict suspects, is too powerful and often works for the benefit of the government in power.

It is under this context that a constitutional amendment bill proposed by Moon removed a clause giving the prosecution the exclusive right to seek warrants.

But what should not be forgotten is that police too are vulnerable to abuses of power and catering to the needs of the government in power. The controversy over Ulsan Police attests to the lingering suspicion about the political independence and neutrality of the nation’s law-enforcement authorities. It is obvious that the most urgent reform is about how to ensure police and the prosecution can operate separately from politics, not realigning or redistributing their powers.