37. ←. In the case of Italy, there is a tension between the rules defined autonomously by the social partners, which define a hierarchical relationship between the levels of collective agreements, and the case law according to which an agreement at company level can always derogate from sectoral agreements. The role of collective bargaining systems for good labour market performance Opening clauses in higher-level agreements were introduced in Germany as a transitional solution42, first limited to working time and then extended to wages from 1995 (Brändle, Heinbach and Maier, 2011). Initially, only the unions were able to agree to revise the contractual conditions, but collective agreements quickly allowed "employment and competitiveness pacts" (BGB) with works councils (with or without the formal participation of a union). These are becoming more widespread and are used regardless of the specific economic situation (Seifert and Massa-Wirth, 2005). Kohaut and Schnabel (2006) also report, on the basis of data from the IAB`s panel of companies, that in 2005, 13% of companies and 29% of employees in Germany were covered by a collective agreement with an opening clause. About half of the companies concerned (53% in the West, 50% in the East) had used such a clause, mainly to change working hours and only a third to change the basic salary or annual bonuses. Data from the WSI works council survey (Schulten and Bispinck, 2014) and the IAB business panel (Addison, 2016) have not yet shown any particular trend over the last ten years, with the exception of one record during the crisis. One of the factors that makes collective bargaining relatively unique from the standard definition of bargaining is that it raises many questions to be addressed. Many types of compensation need to be discussed, including: while the dominant level of bargaining makes it possible to quickly characterise collective bargaining systems in OECD countries, it also risks giving an overly simplified picture. Figure 2.13 clearly shows that countries with the same dominant level of bargaining differ considerably in their actual structure: even in countries where sectoral negotiations are the dominant level, negotiations can play a very important role at company level and vice versa.
A second key element that can distinguish countries with the same degree of convergence is the application of diversion practices. Over the past two decades, controlled forms of derogation have been one of the main drivers of the shift in collective bargaining from centralisation to "organised decentralisation" in some European countries. Temporary opening clauses became quite popular during the crisis (Eurofound, 2015; Visser, 2016), to An to the German practice which, together with other instruments such as short-time working programmes, enabled companies to better adapt to the deep crisis of 2008-2009 (Dustmann et al., 2014). In many OECD countries, the proportion of salaried employees is significantly higher than that of employees who are affiliated to a trade union. .