The issues of proof in the context of a legal action, being in the focus of attention of scholars since the time of Roman law, are still relevant in our days. Recently, the standards of proof in tax disputes appear to be of particular interest, since despite their significance, they remain poorly investigated by scholars and undefined by legislators. However, it is the clearness of the rules or standards of proof in a dispute that is decisive for the validity and legality of a judgment in a particular case. The purpose of the article is to investigate into the legal nature of various standards of proof and their correlation with the judge’s inner belief, and also to define the standards of proof by which an administrative court may be guided while adjudicating tax disputes. Today, the theory of law focuses on the three basic standards of proof – “balance of probabilities” (similar to the American standard “preponderance of proof”), “beyond reasonable doubt” and “clear and convincing proof”. Besides, in practice there may be other standards – “establishment of objective truth”, “beyond a shadow of doubt, “separate reliable proof” etc. Since the standards of proof are not consolidated at the legislative level, several opposing approaches have emerged in the court practice to the definition of such standards in administrative proceedings. The Higher Administrative Court of Ukraine pointed to the possible use of such standards as “beyond reasonable doubt” and “establishment of objective truth” in case of tax disputes. The Supreme Court, in its turn, notes that the courts should play an active part in establishment of objective truth taking all measures possible to verify and establish all of the actual facts relevant to the dispute. However, the legislator denies the standard “establishment of objective truth” in the context of tax disputes. This is evidenced, in particular, by its rules prescribing that evidence may be presented and demanded only before the preparatory proceedings are completed; and also by laying of the burden of proof on the tax authority; impossibility to demand that the taxpayer submit other evidence than those confirming the violation of a right; the lack of grounds for the court to take into account an evidence if the contested regulatory body’s decision has not been based on it. At the same time, the establishment of objective truth is not excluded altogether if all of the evidence is submitted by participants of the legal action upon their own initiative and taken into account by the tax authority in the contested decision. Besides, for most of the tax disputes, the standard “preponderance of proof” is unacceptable, since it would significantly reduce the extent of proving the circumstances of a case on the part of the regulatory body, and this, in turn, would lead to a high risk of violation of taxpayers’ rights and the failure to achieve the objective of administrative proceedings. At the same time, this standard may be used in disputes for recovery of damages from the State, penalties for late VAT refund etc., and this will meet the objectives of administrative proceedings. Obviously, the standard of proof “beyond reasonable doubt” makes a judge choose a more responsible approach to assessing the veracity of circumstances in a case, and this is good for the taxpayer and reduces the likelihood of errors. The ambiguity pertaining to the choice of standards of proof in administrative proceedings may be eliminated by defining these standards clearly at the level of law; however, this does not exclude the possibility of establishing them at the level of judicial doctrine.

List of legal documents 
 

Legislation 
1. Konstytutsiia Ukrainy [Constitution of Ukraine]: Zakon Ukrainy [the Law of Ukraine] vid 28 chervnia 1996 r. № 254k/96-VR. URL: http://zakon2.rada.gov.ua/laws/ show/254%D0%BA/96-%D0%B2%D1%80 (accessed: 18.05.2018) (in Ukrainian). 
2. Kodeks administratyvnoho sudochynstva [The Code of Administrative Judicial Procedure of Ukraine]: Zakon Ukrainy [the Law of Ukraine] vid 6 lystopada 1991 r. № 1798-XII (v redaktsii Zakonu Ukrainy [As Amended by the Law of Ukraine] vid 3 zhovtnia 2017 r. № 2147-VIII). URL: http://zakon3.rada.gov.ua/laws/show/2747-15 (accessed: 18.05.2018) (in Ukrainian). 
3. Podatkovyi kodeks Ukrainy [Tax Code of Ukraine]: Zakon Ukrainy [the Law of Ukraine] vid 2 hrudnia 2010 r. № 2755-VI. URL: http://zakon0.rada.gov.ua/laws/ show/2755-17 (accessed: 18.05.2018) (in Ukrainian). 
4. Pro vykonannia rishen ta zastosuvannia praktyky Yevropeiskoho sudu z prav liudyny [On Execution of Decisions and Application of Practice of the European Court of Human Rights]: Zakon Ukrainy [the Law of Ukraine] vid 23 liutoho 2006 r. № 3477-IV. URL: http://zakon3.rada.gov.ua/laws/show/3477-15 (accessed: 18.05.2018) (in Ukrainian). 

Cases 
5. Västberga Taxi Aktiebolag and Vulic v. Sweden App no 36985/97 (ECtHR, 23 July 2002) accessed 18 May 2018 (in German). 
6. Postanova Verkhovnoho Sudu [Resolution of the Supreme Court] vid 30 travnia 2018 r. u spravi № 815/2143/16. URL: http://www.reyestr.court.gov.ua/Review/74375661 (accessed: 18.05.2018) (in Ukrainian). 
7. Postanova Verkhovnoho Sudu [Resolution of the Supreme Court] vid 30 travnia 2018 r. u spravi № 826/1917/17. URL: http://www.reyestr.court.gov.ua/Review/74407467 (accessed: 18.05.2018) (in Ukrainian). 
8. Postanova Verkhovnoho Sudu [Resolution of the Supreme Court] vid 13 kvitnia 2018 r. u spravi № 826/26667/15. URL: http://www.reyestr.court.gov.ua/Review/73424784 (accessed: 18.05.2018) (in Ukrainian). 
9. Postanova Verkhovnoho Sudu [Resolution of the Supreme Court] vid 7 bereznia 2018 r. u spravi № 825/1682/15-a. URL: http://www.reyestr.court.gov.ua/Review/72718411 (accessed: 18.05.2018) (in Ukrainian). 
10. Postanova Verkhovnoho Sudu [Resolution of the Supreme Court] vid 23 travnia 2018 r. u spravi № 821/2239/16. URL: http://www.reyestr.court.gov.ua/Review/74203920 (accessed: 18.05.2018) (in Ukrainian). 
11. Postanova Verkhovnoho Sudu [Resolution of the Supreme Court] vid 11 chervnia 2018 r. u spravi № 26/4565/14. URL: http://www.reyestr.court.gov.ua/Review/74616809 (accessed: 18.05.2018) (in Ukrainian). 
12. Ukhvala Vyshchoho administratyvnoho sudu Ukrainy vid 13 hrudnia 2017 r. u spravi № 815/4319/16 [Ruling of the High Administrative Court of Ukraine]. URL: http://www.reyestr.court.gov.ua/Review/71031739 (accessed: 18.05.2018) (in Ukrainian). 
13. Ukhvala Vyshchoho administratyvnoho sudu Ukrainy [Ruling of the High Administrative Court of Ukraine] vid 1 lystopada 2017 r. u spravi № 1570/3741/2012. URL: http://www.reyestr.court.gov.ua/Review/70098302 (accessed: 18.05.2018) (in Ukrainian). 
14. Ukhvala Vyshchoho administratyvnoho sudu Ukrainy [Ruling of the High Administrative Court of Ukraine] vid 11 zhovtnia 2017 r. u spravi № 804/4399/16. URL: http://www.reyestr.court.gov.ua/Review/69517761 (accessed: 18.05.2018) (in Ukrainian). 
15. Ukhvala Vyshchoho administratyvnoho sudu Ukrainy [Ruling of the High Administrative Court of Ukraine] vid 27 veresnia 2017 r. u spravi № 2a/0570/2104/11. URL: http://www.reyestr.court.gov.ua/Review/69315517 (accessed: 18.05.2018) (in Ukrainian). 
16. Ukhvala Vyshchoho administratyvnoho sudu Ukrainy [Ruling of the High Administrative Court of Ukraine] vid 20 veresnia 2017 r. u spravi № 813/2642/16. URL: http://www.reyestr.court.gov.ua/Review/69169827 (accessed: 18.05.2018) (in Ukrainian). 
17. Ukhvala Vyshchoho administratyvnoho sudu Ukrainy [Ruling of the High Administrative Court of Ukraine] vid 20 veresnia 2017 r. u spravi № 826/23795/15. URL: http://www.reyestr.court.gov.ua/Review/69169845 (accessed: 18.05.2018) (in Ukrainian). 
18. Ukhvala Vyshchoho administratyvnoho sudu Ukrainy [Ruling of the High Administrative Court of Ukraine] vid 20 veresnia 2017 r. u spravi № 816/5451/13-a. URL: http://www.reyestr.court.gov.ua/Review/69170152 (accessed: 18.05.2018) (in Ukrainian). 
19. Ukhvala Vyshchoho administratyvnoho sudu Ukrainy [Ruling of the High Administrative Court of Ukraine] vid 13 veresnia 2017 r. u spravi № 815/7648/13-a. URL: http://www.reyestr.court.gov.ua/Review/68902399 (accessed: 18.05.2018) (in Ukrainian). 
20. Ukhvala Vyshchoho administratyvnoho sudu Ukrainy [Ruling of the High Administrative Court of Ukraine] vid 5 lypnia 2017 r. u spravi № 813/4076/15. URL: http://www.reyestr.court.gov.ua/Review/67618934 (accessed: 18.05.2018) (in Ukrainian). 
21. Ukhvala Vyshchoho administratyvnoho sudu Ukrainy [Ruling of the High Administrative Court of Ukraine] vid 14 chervnia 2017 r. u spravi № 826/3232/15. URL: http://www.reyestr.court.gov.ua/Review/67194245 (accessed: 18.05.2018) (in Ukrainian). 
22. Ukhvala Vyshchoho administratyvnoho sudu Ukrainy [Ruling of the High Administrative Court of Ukraine] vid 4 zhovtnia 2017 r. u spravi № 825/207/17. URL: http://www.reyestr.court.gov.ua/Review/69388368 (accessed: 18.05.2018) (in Ukrainian). 
23. Ukhvala Vyshchoho administratyvnoho sudu Ukrainy [Ruling of the High Administrative Court of Ukraine] vid 26 kvitnia 2017 r. u spravi № 809/2438/15. URL: http://www.reyestr.court.gov.ua/Review/66271867 (accessed: 18.05.2018) (in Ukrainian). 
 

Bibliography 
 

Authored books 
24. Gadzhiev G, Ontologiya prava (kriticheskoe issledovanie yuridicheskogo kontsepta deystvitel’nosti) [Ontology of Law (Critical Study of the Legal Concept of Reality)] (Norma 2013) (in Russian). 
25. Strogovich M, Kurs sovetskogo ugolovnogo protsessa [A course of the Soviet Criminal Process] (Nauka 1968) (in Russian). 

Edited and translated books 
26. Bruno Leoni, Svoboda i zakon [Freedom and the Law] (IRISEN 2008) (in Russian). 
27. Erlikh O, Osnovopolozhenie sotsiologii prava [Fundamental of the Sociology of Law] (Universitetskiy izdatel’skiy konsortsium 2011) (in Russian). 

Journal articles 
28. Budylin S, ‘Vnutrennee ubezhdenie ili balans veroyatnostey? Standarty dokazyvaniya v Rossii i za rubezhom’ [‘Moral Certainty or Balance of Probabilities? Standards of Evidence in Russia and in Foreign Countries’] (2014) 3 Vestnik Vysshego Arbitrazhnogo Suda RF 25 (in Russian). 
29. Fekhner E, ‘Filosofiya prava’ [‘Philosophy of Law’] (2010) 3 Rossiyskiy ezhegodnik teorii prava 545 (in Russian). 
30. Kaufman A, ‘Ontologicheskaya struktura prava’ [‘Ontological Structure of Law’] (2008) 1 Rossiyskiy ezhegodnik teorii prava 152 (in Russian). 
31. Kolpakov V i Hordieiev V, ‘Dokazuvannia v podatkovykh sporakh u administratyvnomu sudochynstvi Ukrainy’ [‘Evidence in Tax Disputes during Administrative Judicial Proceedings’] [2013] 2(4) Administratyvne pravo i protses 204 (in Ukrainian). 
32. Myroshnychenko Yu, ‘Pro istynnist, dostovirnist i ymovirnist u sudovomu piznanni’ [‘Reality, Veracity and Probability in Judicial Knowledge’] (2016) 3 Visegrad Journal on Human Rights 121 (in Ukrainian). 
33. Sliusarchuk Kh, ‘Standart dokazuvannia v kryminalnomu provadzhenni: yaka yoho ideia?’ [‘Standard of Evidence in Criminal Proceeding: What is the Idea of it?’] (2015) 3 Porivnialno-analitychne pravo 222 (in Ukrainian). 
34. Smol’nikov D, ‘Mify o standartakh dokazyvaniya’ [‘Myths Concerning Standards of Evidence’] (2015) 12 Zakon 199 (in Russian). 
35. Stepanenko V, ‘Standarty perekonannia (dosvid Spoluchenykh Shtativ Ameryky)’ [‘Standards of Evidence (Experience of the United States)’] (2016) 3 Forum prava 248 (in Ukrainian). 

Dissertations 
36. Shcherbakova O, ‘Predmet dokazuvannia v podatkovykh sporakh’ [‘Subject of Proof in Tax Disputes’] (dys kand yuryd nauk, Natsionalnyi yurydychnyi universytet imeni Yaroslava Mudroho 2015) (in Ukrainian).