Dutch 1♣

My approach to respond to the 1♣ opening is a lawyer’s Polish Club. The 2♦ response is natural and game-forcing, while 1♦ is a generic catchall. This way, 1♣ - 2♦ would pass more system regulations around the globe.

System regulations are more liberal in the Netherlands and most of Europe. Dutch players often adopt conventional jump responses. For example, Brink–Drijver and Rosalind Hengeveld play the Multi 2♦ response.

In countries with more conservative regulations, conventional jump responses are restricted. On the other hand, artificial 1♣ - 1♦ is often tolerated. The ACBL Basic Chart and 🇯🇵 JCBL Convention List C explicitly allow any 1♦ response to a constructive 1♣.