He conducted research for a semester at the University of Giessen, where passed the exams of pathology and food microbiology.

In it he confirmed the claims by opposition politicians and journals that the ruling Fidesz government awarded national tobacco sales rights based on party connections, and favoring local pro-government politicians including the mayor of Szekszárd, István Horváth.

[4] Horváth denied the charges but HVG presented a leaked audio recording from an assembly of the local representative body, which strengthened Hadházy's allegations.

The news portal quoted Horváth who said it was most important that "applicants should be committed conservatives" and "socialist supporters must not win [at the tendering process]".

After that Hadházy submitted a protest against the result in the Regional Court of Pécs, presenting evidences about organized tours of voters.

[9] He launched a portal korrupcioinfo.hu and held weekly press conferences, where uncovered numerous alleged corruption cases involved Fidesz politicians and government—close businessmen and bankers.

After the LMP's most well-known politician, András Schiffer announced his retirement from politics, Hadházy was elected co-chair of the party on 16 July 2016, alongside Bernadett Szél.

[2] Hadházy criticized the Orbán government's migrant quota referendum campaign in October 2016; he called the referendum as "destructive", because it "whipped up panic-like fear" among the citizens, while distracting from the "collapsing health care" and the "looting of EU funds at state level".

[11] During the campaign period of the 2018 parliamentary election, Hadházy was a strong advocate for cooperation among left-wing opposition parties despite the LMP's contradictory resolutions.

[12] Despite Tamás Harangozó (MSZP) withdrew his candidacy in favour of Hadházy, he again lost to Fidesz MP István Horváth in Szekszárd constituency.

[13] As the governing Fidesz–KDNP won a two-thirds majority in a row for the third time, Hadházy resigned as co-leader of the LMP at the night of the election day.