Bulgaria's ruling Citizens for European Development of Bulgaria (GERB) party has proposed a constitutional amendment that will strip lawmakers of their immunity from detention or prosecution. The proposal was triggered by the latest of a series of public offences by MP Volen Siderov, leader of the far right Ataka party.

The move is motivated by the bizarre behaviour of a single MP from one of Bulgaria’s smaller opposition parties. However, if adopted it would provide a valuable tool for the fight against high-level corruption in Bulgaria, which has lagged behind neighbouring Romania. In September, MPs rejected a draft law which would have set up a single body to fight high-level corruption.

MPs are due to discuss the new proposal from Prime Minister Boyko Borissov’s GERB after Siderov reportedly harassed students from the National Academy for Theatre and Film Arts (NATFA) in Sofia on several occasions. Claiming he had information about drug dealing and drugs hidden in the building, he made several personal inspections at small shops around the university.

Late on October 23, Siderov, his deputy Desislav Chukolov, also an MP, and around a dozen supporters entered NATFA's building, and allegedly shouted insults and tried to beat students.

Two days later, after polls closed in Bulgaria’s local elections, Siderov and his supporters again visited NATFA, angering students and local residents. Footage from Kanal 3 TV shows police saving Siderov from the angry crowd, but not before a man manages to hit him in the face.

Siderov’s Ataka has 11 lawmakers in the 240-seat assembly. During the previous administration, it was an occasional supporter of the ruling Bulgarian Socialist Party (BSP) although there was little common ground between the two parties.

On October 26, Bulgaria’s prosecutor general Sotir Tsatsarov asked the parliament for permission to detain Siderov and Chukolov in connection with the October 23 accident. This is the third time Tsatsarov has attempted to deprive the nationalist leader of immunity.

The parliament will discuss the proposal on October 28, and opponents to the move are already mobilising. Some 500 people rallied in Sofia in the evening of October 26, demanding that Siderov retain his immunity.

There are also indications of divisions within the ruling coalition. Justice Minister Hristo Ivanov warned that a potential amendment to the constitution should be made very carefully and advised against abolishing lawmakers' immunity altogether. Instead, he called for a firm and prompt institutional response to the accident.

In April 2015, the Bulgarian government announced plans to set up a single authority to tackle corruption, following criticism from the European Commission. The main step envisaged under the National Strategy for Prevention and Combating of Corruption was the creation of a single body to take over the operations of existing anti-corruption agencies. Borissov said at the time that he wanted Bulgaria to overtake Romania in its anti-corruption efforts within four months.

However, in September the Bulgarian parliament rejected in its first reading a bill on the creation of the new independent body. The bill was supported only by the ruling party GERB and its coalition partner the Reformist Bloc. Ataka was among several parties whose MPs abstained in the vote, while the BSP voted against the measure.

Sofia is also under pressure from the European Commission to accelerate anti-corruption reforms. Bulgaria made slow progress on judicial reform and tackling corruption and organised crime last year, according to the European Commission’s January 2015 report on progress under the Co-operation and Verification Mechanism (CVM), a tool created to assess steps taken in Bulgaria and Romania in these areas.