For anyone who cares about the climate crisis, public lands, clean air and water, or any other environmental issue, Donald Trump’s policies have been catastrophic. But horrible though they are, Trump’s policies are not why the Sierra Club supports the impeachment inquiry now underway in the House of Representatives. We’ve opposed the policies of other presidents—but always by harnessing the power of democracy and invoking the rule of law.

It’s Donald Trump’s flagrant contempt for those foundations of fair government that makes this different. You can argue about when it became undeniable that Trump does not care about his oath to preserve and protect the Constitution and the United States, but his admission that he asked a foreign power to investigate a political opponent no longer leaves room for doubt: This is a man who will do anything—including abusing his power, obstructing justice, and operating outside of the rule of law—to protect himself.

Here’s how that affects the Sierra Club (and all of us): If our democratic norms and the law mean nothing, then the legal and democratic tools that we use to protect clean air and water, public lands, and a safe climate will also become meaningless. The Sierra Club—and every other group working for positive change in this country—requires a functioning, law-abiding government and democratic access to that government. Without that, we can’t protect people or the environment.

For the American people, though, the stakes are even higher. This is a struggle between deceit and transparency. Between corruption and integrity. Between darkness and light. To defend our democracy and restore the integrity of our institutions, Congress must carry out its constitutional duty to fully investigate this president’s actions and hold him accountable.

It’s no time to be silent. Take action now to tell your representative that you support full impeachment hearings in the House of Representatives.