Joshua A. Douglas is a law professor at the University of Kentucky College of Law who specializes in election law and voting rights. He is the co-editor of " Election Law Stories ." Follow him on Twitter @JoshuaADouglas . The opinions expressed are his own.

(CNN) First, Trump's press secretary, Sean Spicer, misrepresented how many people watched Trump's inauguration, saying it was the largest crowd ever to witness the swearing-in of a new president, despite clear photographic evidence to the contrary. Then, Trump said there were 3 to 5 million illegal votes in the election, costing him the popular vote. Spicer doubled down on this lie in his press briefing, citing debunked theories about voter fraud.

The first falsehood, on the crowd size, is no big deal in the grand scheme of things, beyond undermining Spicer's credibility. The second lie, on voter fraud, exhibits a disturbing pattern and also lays the groundwork for an assault on voting rights.

In the 2000 election, Republican John Ashcroft narrowly lost a US Senate election in Missouri to Democrat Mel Carnahan, who had died in a plane crash shortly before Election Day. On election night, Missouri's senior Senator, Republican Kit Bond, screamed at an Ashcroft rally that "dogs and dead people" had cost Ashcroft the election. He pounded the podium and declared, "This is an outrage!"

Bond had no evidence for his claim that voter fraud had swung the result. But he continued making these arguments on the Senate floor during the debate over the new Help America Vote Act of 2002 , which was Congress' response to the 2000 election debacle. He often pointed to the case of Ritzy Mekler , a springer-spaniel who supposedly was on the voter registration rolls in St. Louis. (Although Ritzy may have been on the registration rolls, there is no evidence that she actually voted). Ultimately Bond persuaded his fellow Republicans to support a federal voter ID requirement for first-time voters who registered by mail.

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Republican-controlled states then took the mantle, passing their own stricter forms of photo identification laws that allow fewer and fewer documents to serve as valid IDs for voting. In 2004, Indiana was the first state to enact a strict photo ID law once Republicans took over the governor's mansion and both houses of the state Legislature for the first time since 1982.

Once again, Indiana politicians claimed they were trying to root out voter fraud, this time pointing to election fraud in a local Democratic primary that involved absentee balloting. Of course, a photo ID requirement for in-person voting would not prevent absentee balloting fraud. Nevertheless, Indiana's law, which the US Supreme Court refused to overturn in 2008, served as a model for the rest of the country. Photo ID laws spread, becoming the most significant election administration issue of the past decade, all resting on initial falsehoods about the extent of voter fraud.

States continue to pass strict photo ID requirements that do not prevent any known voter fraud. The requirements instead disenfranchise valid voters who simply do not have the required ID or would suffer significant hardship in obtaining one. One court found that Texas' law could disenfranchise up to 600,000 valid voters and would disproportionately harm minority populations. Courts throughout the country last year required states to "soften" their laws to try to prevent disenfranchisement. But that did not solve all problems, as confusion and uneven implementation still affected many voters.

JUST WATCHED Chalian to Trump: Provide proof of voter fraud Replay More Videos ... MUST WATCH Chalian to Trump: Provide proof of voter fraud 01:09

Trump's frequent allegations of voter fraud in the 2016 election are not simply innocuous rhetoric from a president upset that he lost the popular vote. It follows a pattern of repeating false claims about voter fraud in an effort to make the public believe something that is verifiably not true. Many Americans think that voter fraud is rampant, despite clear evidence to the contrary. This is probably why most Americans support a voter ID requirement. But the fact is that in-person impersonation -- the only kind of fraud a photo ID law would root out -- is extremely rare , while disenfranchisement because of strict voter ID laws does occur.

Trump's team members seem to think that if they say it enough times, it must be true. They are banking on the American public actually believing that there were millions of illegal votes, meaning that we have to do something about it. We must not forget: This tactic has worked before, leading to the passage of voter ID laws in dozens of states.

Although we should do more to streamline the registration process, the fact there may be excess people on the voter registration rolls makes perfect sense under our current system. People move, die and sometimes there may even be improper names when workers conducting voter registration drives are paid per registration and wrongly seek to pad their numbers, without any concern that these people actually vote. Yet the general public will probably think something is amiss simply because the federal government is conducting an investigation.

The fact is that actual voter fraud on Election Day, although sometimes present in small numbers in local elections, did not materially alter the presidential election. Even the studies Spicer cited to justify Trump's claim of millions of illegal votes mostly discussed problems with voter registration, not noncitizen voting.

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Voter fraud occasionally occurs through absentee balloting or even complicit poll workers, but it is absurd to claim that 3 to 5 million illegal votes -- conveniently a number higher than Hillary Clinton's 3 million popular vote lead -- changed the popular vote in the presidential election, which, in any event, does not have any relevance to the outcome beyond hurting Trump's ego. Even more dangerous is the incorrect message it sends about the extent of voter fraud and the need to enact measures to combat it.

Trump's lies in his first few days are therefore dangerous not only because they undermine the public's faith in the truth of any future message coming from the White House. They also are part of a plan to persuade the public of something that is verifiably wrong so the administration can justify future efforts at partisan-laden voting laws that will harm the right to vote.