[5] From January 2002 to May 2003, he was the director of the law firm Portnov and Partners, specializing in services in the field of investment business, corporate governance, privatization and the securities market.

[18] Portnov is called the initiator of the development of the so-called "dictatorial laws" of 16 January 2014, which significantly limited the constitutional rights of Ukrainian citizens and were directed against Euromaidan.

[19][11][12][20][21] I did not take part in writing these laws, but as an official of the presidential administration at that time, due to my functional responsibilities, I also put my visa when they came from the parliament to be signed by the president.

[27] On 5 March 2014, the European Council approved the blocking of a total of 17 former government officials and people close to former President Yanukovych on suspicion of misappropriation of budget funds.

[31][32] On 25 August 2014, the Pechersky District Court of Kyiv partially satisfied Portnov's claim against the Prosecutor General's Office of Ukraine for the protection of honor, dignity and business reputation, ruling to declare unreliable information about his alleged involvement in the massacres of activists at Euromaidan during the early winter events of 2014.

[33][34] On 9 October, the court ruled unreliable information about Portnov's alleged involvement in the plundering of land and real estate in Mezhyhirya and the legalization of funds, made public by the leadership of the General Prosecutor's Office of Ukraine addressed to him at a press conference on May 20 and ordered the General Prosecutor's Office of Ukraine within 10 days to receive this information publicly refute.

In the fall, the European Union received a written message that the Ukrainian law enforcement agencies had no procedural actions against the Klyuyev brothers and Portnov on charges of embezzlement.

[38] In October 2015, the EU court ruled in the case of Portnov v. European Council, recognizing that the imposition of sanctions solely on the basis of cooperation with the previous regime was unacceptable.

[39] On 5 May 2015, Portnov, along with Oleksiy Azarov, and former Security Service of Ukraine (SBU) leaders Oleksandr Yakymenko and Ihor Kalinin were removed from the EU sanctions list.

[44] У листопаді 2019 року представники канадського уряду повідомили журналістам[45] In November 2019, representatives of the Canadian government told reporters that Canada could lift sanctions on Portnov if the Prosecutor General's Office of Ukraine does not provide grounds for their extension.

[46][47] On 27 November 2019, the Prosecutor General of Ukraine Ruslan Riaboshapka announced in the Verkhovna Rada that the GPU is still negotiating with the official authorities of Canada on sanctions against Portnov, but did not provide details.

[50] From 27 August to 5 October 2018, he was the owner of the corporate rights to the news channel NewsOne, which eventually passed to the business partner and political associate of Viktor Medvedchuk, and Taras Kozak.

[17] During the 2019 presidential election, Portnov spoke in support of Volodymyr Zelensky as opposed to incumbent President Poroshenko, and after both went to the second round, he promised to return to the country.

[37][56][57] After that, he began filing applications with the State Bureau of Investigation against former President Poroshenko: accusations of "criminal actions" during the 2018 Kerch Strait incident, "economic crimes", illegal purchase of the Pryamiy kanal TV channel, "seizure of power" during the election of the Groysman Government in 2016.

[63][64][65] Viktor Andrusiv, the executive director of the Ukrainian Institute of the Future, accused Prosecutor General Yuriy Lutsenko of inaction because Portnov had returned freely and had not been summoned for questioning, including on the January 16 laws.

Students of the educational institution announced protests against such a decision, the next day the rector of the educational institution announced the cancellation of the decision to hire Portnov.,[71] на следующий день ректор учебного заведения сообщил об отмене решения о найме Портнова[72] On 21 June 2019, the host of the Crime and Punishment program on NewsOne, co-host - TV channel producer, Vasiliy Holovanov, also participated in the Epicenter program[clarification needed].

The court's decision is due to the fact that on 14 April 2014, Portnov got the position of director of the department for legal assistance abroad in the law firm "Corporate Technologies".

[81] After a year of Zelensky's presidency, the country is witnessing the emergence of a strong non-parliamentary opposition, which believes that the replacement of “new and inexperienced” personnel in power with such professional and consistent ones as Portnov can bring Ukraine out of the crisis.

[82] On 17 June 2020, Portnov, commenting on the most relevant topics in the Ukrainian Format program on the NewsOne TV channel, formulated the necessary urgent measures to consistently fight the radical gangs.

[83] From the beginning of February and at the end of June 2020, Portnov won lawsuits against Poroshenko, his party, European Solidarity, and the Pryamiy kanal TV channel in court.

[84][85] On 8 January 2021, Portnov criticized those who, using double standards, deny the clear similarity between the 2021 United States Capitol attack and the Ukrainian Euromaidan, which the Democratic Party actively supported in 2014.

The editors considered this publication to be direct pressure on the Scheme team, which was preparing an investigation into Portnov's influence and his connections with the new Ukrainian government, as well as a violation of a number of articles of the law on the protection of personal data and the Criminal Code.

[92] According to the Schemes: Corruption in Details project of Radio Free Europe/Radio Liberty, on June 3, 2022, during the Russian invasion of Ukraine, Portnov fled the country[93] through Zakarpattia Oblast.

[27] On 15 August 2014, the Pechersk District Court of Kyiv partially upheld Portnov's lawsuit against the Prosecutor General's Office of Ukraine for protection of honor, dignity and business reputation, ruling that the information about his alleged involvement in mass killings of activists during the 2014 Ukrainian revolution during the 2014 winter events was unreliable.

[17] In January 2018, during a hearing of the Obolon court in the case of treason against former President Yanukovych, prosecutors published a telephone conversation between Russian presidential adviser Sergey Glazyev and a certain "Vladimir Andreevich", recorded by Ukrainian intelligence on 1 March 2014.

During the conversation, Glazyev informed about the need for the Verkhovna Rada of the ARC to adopt a resolution prepared by Portnov, a Ukrainian lawyer and former deputy head of the Presidential Administration.

Criminal proceedings have been registered for four episodes of Portnov's activity - statements on the incident with Ukrainian sailors in the Kerch Strait, on the TV channel "Pryamiy", on "Kuzny na Rybalskomu" and on the High Council of Justice.

[118] In November 2019, the national police registered a criminal case against Portnov, accusing him of pressuring the editorial board of the "Schemes: Corruption in Details" program (Radio Libertu project).

In addition, in order to illegally influence the judicial system of Ukraine, Portnov became a member of the High Council of Justice as a representative of a higher education institution.

[137] In November 2019, the journalistic project "Slidstvo.Info" reported that since 2017, Portnov, through social networks and instant messengers, has dealt with threats to prosecutors who worked on criminal cases with his participation.