(CNN) President-elect Donald Trump has a habit of saying outrageous things that suggest he wants to clamp down on free expression in the United States. He once advocated "open[ing] up" the libel laws so he could sue media organizations that falsely criticized him. The other day, he suggested we should punish flag burners and even strip them of their citizenship.

Despite the outcry his statements have generated, Trump probably can't change the libel laws very much, and if he did, he'd probably be the one sued for his false statements. Under the Supreme Court's decision in Clinton v. Jones, presidents aren't immune from civil suits while in office. Similarly, the Supreme Court has made clear that flag burning is protected speech, and that the government can't strip a person's citizenship as punishment for a crime.

Even so, we shouldn't lose sight of the fact that our soon-to-be president could weaken the American system of free expression in far more troubling and insidious ways. They don't involve throwing dissenters in jail; many of them don't even require significant changes in the law. Rather, they are techniques that involve weakening and undermining the institutions and practices that enable public opinion to check state power and legitimate our system of democracy.

The first technique is lying repeatedly and with impunity. Politicians dissemble about a lot of things, but a successful democracy requires they pay a price for it. Our new President, however, has found a way to lie so boldly and so frequently that it's virtually impossible to hold him to account.

If politicians lie all the time, and never pay a price for it, there's no reason to believe any promises they make. Ironically, Trump's serial mendacity doesn't significantly undermine his credibility — instead, it undermines the credibility of his political opponents. Trump's supporters accept that Trump is just exaggerating, but they figure that because his opponents are professional politicians, they must be lying, too. Nobody can be trusted, so facts don't matter. The ability to lie with impunity severs the connection between public opinion and how officials exercise state power. It undermines democracy.

A second and related technique is propaganda. We usually associate propaganda with communist dictatorships. But the 2016 election has shown that it works right here at home. Trump and his media allies waged a successful propaganda campaign during the recent election season, but perhaps equally important was a flood of propaganda from his supporters, not only from inside the United States but directed at US audiences from foreign countries. Propaganda mills in Eastern Europ e, for example, pushed out false news reports through social media.

Flooding the media space with false stories confuses the public and further undermines the connection between public opinion and democratic authority. Ironically, in order to cover day-to-day politics, responsible media organizations find themselves referring to these stories, thus propagating them further.

A related technique is gaslighting , creating a false reality and causing the public to doubt what is actually true or false. By making everything uncertain and a matter of ideological perspective, government officials stoke anger and distrust in elite institutions on the one hand, and produce cynicism, resignation and despair on the other. Propaganda and gaslighting produce a public that trusts no one, lacks faith in government and therefore expects little from it.

A third technique is taming the media. Trump is a master media manipulator. Recognizing that our free market system makes for-profit media captive to advertisers and thus to ratings, Trump has made himself indispensable because he can grab audience attention and generate ratings by saying and doing outrageous things. News media have become addicted to Trump, and his power to command attention will only increase once he becomes President. At the same time, Trump complains loudly about unfair media treatment, and threatens to deny access to journalistic organizations that cross him. Through this combination of carrots and sticks he hopes to render the institutional media docile and pliable. He will be assisted in these efforts by conservative media organizations like Breitbart, and commentators like Fox's Sean Hannity, who functioned as unofficial propaganda arms of the Trump campaign and will now support the Trump White House.

A fourth technique is opacity. A determined White House can shield many of its operations from scrutiny, denying the press and the public access to information about what the government is doing and why. Over the years, presidents have developed increasingly sophisticated ways to divert media attention and manage media access, maintain secrecy and circumvent legal guarantees of freedom of information. These techniques undermine democracy because they prevent the press from informing the public about government malfeasance and how state power is actually being used.

President Trump will expand on the techniques of his predecessors, especially because, unlike most of them, he has incentives to avoid inquiry into conflicts of interest between his business dealings and his conduct of foreign and domestic policy. As a general rule, the more presidents have to hide, the more we should expect that they will constrict access to information. Judging by the 2016 campaign and the first weeks following the election, Donald Trump has a great deal to hide.

The fifth and perhaps most troubling technique is surveillance. Even in the mid-20th century the executive branch contained the investigatory and prosecutorial resources of the FBI, the CIA, the Justice Department, and the Internal Revenue Service. Each of these institutions constructed formal and informal rules and norms designed to prevent abuse by the White House. But as Richard Nixon's presidency demonstrated, these rules and norms don't always work, and given enough time, a determined President can chip away at or circumvent many of them.

In the past 20 years the United States has created what I have called the National Surveillance State , which governs our lives through the collection and analysis of information. The official justification for building many of these capacities was the War on Terror; but the techniques and technologies outstrip this particular goal. Today the executive branch can monitor many different aspects of our lives.

The more powerful our surveillance state becomes, the more susceptible it is to misuse by government officials with bad motives. Moreover, if a President cultivates a reputation for vengeance against those who cross him, he doesn't even have to do very much. Because the system of government surveillance is secret, people will expect the worst and fall in line. Merely conveying the message that the administration might be watching its opponents will chill speech, political association and political organization, undermining the freedoms through which Americans hold their leaders to account.

Follow CNN Opinion Join us on Twitter and Facebook