The countries of Central and Eastern Europe work over the adaptation problems of legislation to the requirements of western market economy and the European law. The harmonization of national legislation and EU standards is one of main factors while accessing the European Union that is why the majority of members form and try to realize new laws during rather shot time. In such conditions it is impossible to avoid sub-optimal and unsustainable solutions, unpredicted costs for law realization and side effects. In many cases such law acts is mostly impossible to put in practice. In EU to deal with such problems the mechanism of legislation adaptation and harmonization was introduced with the name "impact assessment”.

The main object of research is an analyzing of developed countries experience in EU in a process of adaptation problems of legislation within the European Union. EU member countries began to adopt the method of "impact assessment" for the legislative program two decades ago, paying attention to the fact that using new laws may have unpredictable effects not only for the state budget, but also for various aspects of economic and social life. Nowadays, EU member countries have agreed that influence assessment should be partially conducted at the stage of new legislation designing. Assessing the impact of the policy instruments development for these countries is mandatory for many years.

These requirements were usually represented in the general rules of government agencies, which included a list of issues and recommendations regarding the implementation of assessment. This is usually driven by the following rule: no proposal is not filed in the Ministry or the Cabinet of Ministers without a document that certifies the need for the decision and documents the results of impact assessment. However, the existence of such influence in the EU member states does not mean that this requirement is met fully and professionally.

Every year the value of such impact assessment increases in the legislative sphere and policy. Impact assessment is information-analytical method of defining possible costs, consequences, side effects of planned policy instruments (laws, regulatory acts, investment programs etc.). Furthermore it is possible to put in practice the impact assessment when the instruments were already realized. In any case the results are used for improving the quality of making policy decisions and elaboration of policy instruments. In general – it is a way of informing the Government about the possible decisions.

The impact assessment is a mechanism of informative base providing at every stage of policy cycle that contributes for making better policy decisions. As this mechanism provides a data about possible consequences of new political instruments or real consequences of some policy, it also influences on the process of state reforming and modernizing. Besides, it is an instrument of regulatory legislative base of the country. The objective of impact assessment realizing has two points:

1. political instruments improvement;

2. decrease of number of legislative instruments, avoiding making unnecessary laws and regulatory acts.

Therefore the experience of national legislative harmonization in the space of European society gives the ability to put in practice impact assessment method while adaptation local legislative bases to the European laws for EU countries candidates.