Ukraine's Constitutional Court has struck down a law against officials enriching themselves, a move that raises concern about the country's fight against endemic corruption and about whether it can get further aid from the International Monetary Fund.

The Ukrainian branch of Transparency International said Wednesday that the decision means at least 50 corruption cases will have to be closed.

The court said the law was unconstitutional because it violated the presumption-of-innocence principle by obliging suspected officials to prove their assets were legitimate, rather than obliging prosecutors to show assets were obtained by corrupt practices.

The law was introduced in 2015 to meet a demand of the IMF in order to receive badly needed loans. The IMF in 2015 authorized $17.5 billion in aid to Ukraine to support reforms.