Constituents Retain Primary Constitutional Powers
Providing the electorate maintains the primary power to build a constitution, constituents can take away the constitutional delegation from the judicial branch at any time.
Consider this example. A nation has had an unamendable constitution for 200 years that grants a judicial branch legislative oversight. The executive and legislative branches, with the support of the electorate, wish to amend a section of the constitution. After passing the amendment through the legislative and executive branches the judicial branch deems the amendment unconstitutional under the terms of the initial constitution (which prohibits constitutional amendments).
The executive and legislative branches, with the support of the electorate, could then write a new constitution to replace the old constitution. This constitution could be amendable, granting future generations both primary constituent powers (who can write a new constitution) and secondary constituent powers (the ability to make amendments), thereby returning the judicial branch’s role to constitutional preserver, rather than interpreter.
The Judicial System Is Upholding A Democratic Constitution
Making the judicial system the protector of an unamendable constitution is compatible with democracy. The judges, while not democratically elected themselves, are protecting a constitution that was written by a democratically elected government.
While they may not have the majoritarian support at that moment, they are acting in accordance with the will of the political supermajority at the time the constitution was written.
In this light, when judges protect an unamendable constitution, they are protecting the will of the people and democratic processes, albeit not the current will of the people.