Over the past decade, public procurement goals have expanded from obtaining free competition and lowest prices to achieving objectives of “horizontal” policies that take into account ecological and social aspects. However, the Tinbergen Rule states that one instrument should be matched with one goal, while using one instrument for achieving multiple goals would undermine its effectiveness. In this paper, we will examine whether implementation of “horizontal” public procurement policies related to green public procurement, socially responsible public procurement and the promotion of micro, small and medium enterprises’ participation affect achievement of the “primary” public procurement goal of free competition. Our study is based on empirical data on more than 65,000 public procurements carried out in Slovenia during the period 2016-2019.