Western liberal democracies have Constitutions against which the Courts are able to determine if legislation passed by a governnent is constitutional. The Courts can strike down legislation they consider unconstitutional. Its called the separation of powers. It will be interesting to see how the Israeli court system handles this little gem.
UN: Gaza could be 'uninhabitable' by 2020 if trends continue (AP)
from the article: Why Israelis must fight against the boycott law