In 1965, a private investigator named Harold Lipset appeared before a Senate subcommittee and took a sip from a martini. That part was a little unusual, but it was what the glass contained that shocked lawmakers. The pimento in the facsimile of an olive concealed a miniature recording device; the toothpick was an antenna. Near the end of his testimony, Lipset played back his own opening statement. He had been recording the whole time.

Lipset, who was known for such stunts (he’d once recorded a naked man in a bathhouse by bugging a bar of soap—though, for the record, his “pry martini” did not actually contain gin or vermouth), was there at the invitation of Missouri Senator Edward V. Long, who was pushing for an end to the congressional gridlock over privacy legislation. Three years later, a watershed law was passed—but instead of securing the privacy of Americans, it gave police at the state and federal level the legal right to wiretap them. That provision reshaped the relationship between law enforcement and private citizens and laid the foundations, both legally and socially, for our current surveillance state.

According to Brian Hochman’s The Listeners: A History of Wiretapping in the United States, Americans have held many attitudes toward surveillance over the years. The latest, which has calcified since police wiretapping was enshrined into law in 1968, is indifference. Wiretapping was once seen as extraordinary: Americans in the early 20th century considered it a “dirty business.” Then some attitudes shifted, and by the postwar era, many private citizens were already using freelance tappers in divorce disputes. (Hochman drops the astonishing tidbit that in the 1950s in New York, “Private ears tapped more lines to monitor cheating spouses than their counterparts in law enforcement did to gather criminal evidence.”) By the 1960s, Americans were divided, with law-and-order conservatives arguing that police needed the right to surveil and progressives pushing to protect privacy.

The fraught relationship between privacy and security is at the crux of The Listeners, which covers the history of eavesdropping from the Civil War to 9/11. Throughout that long history, the threat—real or imagined—of crime almost invariably took priority over civil liberties. Racist dog whistles shaped surveillance laws in 1968, and people of color historically bore the brunt (and still do) of police surveillance.

Hochman does not address our current world of digital surveillance beyond a handful of brief passages that bookend his study. Though he discusses certain laws, especially those from the 1990s, that laid the groundwork for phone surveillance, he declines to explore explicit parallels; rather, he focuses on the “analog past.” As he writes in his introduction, “I leave it to the reader to decide whether that past can help us find a way out of our current predicament.” His thoughts on the matter would have been welcome, too.

Instead, Hochman bases much of his analysis on the changes in public opinion in the 20th century. But who exactly this public opinion represents is not always clear. “Our historical amnesia,” Hochman argues, “prevents us from seeing that digital surveillance didn’t always seem so pervasive and routine.” Pervasive and routine for whom? Who comprises “us”?

It’s worth asking because Hochman concerns himself with the type of surveillance that stretches its tendrils into ordinary people’s lives—what he calls the “prosaic” dimensions of eavesdropping. Although a few hardboiled detectives and operatives appear in these pages, for the most part the book is a history of people intersecting with wiretaps and the law. Hochman has a strong eye for amusing, illustrative characters (such as Lipset), which provides welcome color to his explanations of thorny legal cases.

Throughout the 20th century, new ways to talk on the phone meant new ways to bug. Lawmakers were generally not as agile as motivated criminals in catching on to technological developments (especially when physical wiretaps gave way to stand-alone bugging devices and wireless phones). New devices led to legal questions both procedural and profound: Do police need a warrant to tap a suspected Soviet spy? Are clandestinely gathered communications admissible in a court of law? Does a recording of your voice count as property under the Fourth Amendment? Can a man bug his spouse if she’s using his phone for deleterious ends?

Before 1968 especially, wiretapping laws were a morass. Even when such laws were on the books, their confusing wording caused interpretative chaos. In a particularly infamous example, a single word wreaked havoc for decades: “and.”

In 1934, Congress passed the Federal Communications Act. Section 605 of the law, which addressed wiretapping, contained the line: “No person not being authorized by the sender shall intercept any communication and divulge or publish.” Yet that “and” could be read two ways. In the first interpretation, the line was tantamount to a blanket ban on wiretapping; in the second, it meant that it was only illegal to wiretap if you also shared the recording. In 1937, the Supreme Court ruled in favor of the first interpretation. But despite that ruling, Hochman writes, the section continued to prove “nothing short of catastrophic” when it came to preventing wiretapping. The whole thing was so muddled as to be rendered meaningless. In the absence of federal regulations, jurisdictions developed their own laws in response to local preferences and influences.

Cities and states had their own patchwork regulations, although these too were only inconsistently followed. Police often had a “gentleman’s agreement” with local phone companies that enabled them to tap lines without producing a paper trail.

In 1959, a lawyer named Samuel Dash made a splash in Washington with his bombshell report “The Eavesdroppers,” which was funded by a grant from the Ford Foundation–affiliated Fund for the Republic, on the state of surveillance in America. Dash broke with previous analyses, which tended to blame individual wiretapping agents or the vulnerability of phone systems, to point a finger at the incoherent laws around surveillance in the United States. Hochman explains that, in Dash’s view, wiretapping law was “a legal no-man’s land,” and the contradictions in wiretapping policy were exacerbating the nation’s “looming privacy crisis.” Such revelations were not merely a policy concern—they raised real questions about American values. What kind of a society allowed police to wiretap in open defiance of state and federal laws?

With his report, Dash—who later served as chief counsel to the Watergate Commission—helped provoke a “momentous swing in popular perception during the late 1950s and early 1960s,” Hochman writes.

“The Eavesdroppers” proved to be divisive. A vocal contingent saw the report as an attack on police and their law enforcement tools. One Brooklyn district attorney fretted that wiretapping bans would give criminals “carte blanche” in their operations. He suggested that what wiretapping really needed was a rebrand. Rather than calling it “eavesdropping,” which sounded nefarious, he suggested that a new name be adopted to indicate that it was actually the use of “scientific devices to fight crime.”

It was against this backdrop that Senator Long, who had invited Lipset to perform his martini stunt, attempted to push legislation that would ban police wiretapping. He had reason to be optimistic that his Right to Privacy Act of 1967 would pass: President Lyndon Johnson had expressed an interest in curbing wiretapping in his State of the Union address that year, in which he called for an end to all wiretapping “except when the security of the nation itself is at stake.”

Then came the “long, hot summer” of 1967. Unrest in American cities over the next year provided an opening for law-and-order politicians to make dog-whistle calls about wiretapping as a riot prevention tool. Conservatives in Congress, led by the hardline segregationist John L. McClellan, added police wiretapping authorization to the Omnibus Crime Control and Safe Streets Act of 1968. “Few lawmakers saw the wisdom in impeding the most sweeping public safety measure to come out of Washington in decades,” Hochman observes, especially after Robert F. Kennedy’s assassination. Johnson, although he had already announced that he would not run for reelection against the Republican challenger, Richard Nixon, nonetheless caved. For elected officials, an aversion to wiretapping proved less powerful than racist rhetoric in a fraught moment. The omnibus bill passed, and Long found himself “politically radioactive.”

Title III, the part of the act that concerned wiretapping, was monumental (and continues to loom large in privacy law today). In an interesting compromise, it both criminalized private-sector tapping and legalized police tapping. The bill included some guardrails, including that police needed to attempt other means of gathering evidence before starting a tap and, notably, that they needed a warrant in most cases (though McClellan squeezed in an exception for 48 hours of unwarranted surveillance in “emergencies”). Privacy advocates cheered the private-sector restrictions, but the allowances for the police “exceeded even Long’s worst fears.” Yet soon, Hochman argues, “No one seemed to care.” Again: No one?

Police wiretapping exploded in the following years. Warrants for tap and bug installations increased fivefold at both the state and federal level. Hochman cites compelling evidence of shifts in public opinion here: According to a 1974 Chicago Tribune report, nearly 70 percent of Americans condoned the use of electronic surveillance by the police when done with a proper warrant (up from the 46 percent who had felt that way in the late 1960s, according to a Gallup poll). “Almost overnight,” Hochman concludes, “what was embattled became mundane.”

Wiretapping was not an investigative panacea, however, and it was enormously resource-intensive. After an attempt to surveil Teamsters president Roy L. Williams in the late 1970s cost more than $1 million and ensnared the calls of more than 2,000 people in its dragnet, some questioned whether wiretapping was really the most efficient use of government funds.

Then the War on Drugs provided the perfect justification. Law enforcement around the country claimed that sophisticated drug-trafficking syndicates required intensive surveillance. The wiretap had a “comeback” in the 1980s, and Black communities were harmed the most. “Once again, arguments about the costs of electronic surveillance would disappear when African American voices were caught on the line,” Hochman notes.

People of color continued to be the targets of unequal surveillance in the decades to come. In what was a “transparent product of the drug war’s racial geography,” Hochman writes, in 1995 the FBI called for a tiered system of surveillance that would allow one out of every 100 phones to be tapped in certain urban areas. This schema was rescinded after a public backlash. But it illustrates how deeply the surveillance of Black people was embedded in policy at every level of government (even beyond the well-known operations like COINTELPRO, which Hochman mentions briefly). The specter of police wiretapping was a reality of everyday life for many people in Bill Clinton’s “tough on crime” America.

Buried in a major 1994 law, the Communications Assistance for Law Enforcement Act (CALEA), was a provision that would have profound effects as surveillance technology evolved: Phone companies had to comply with court orders to grant the government access to call location data. Cell phones were turned into surveillance beacons. Hochman writes that this “would have consequences for the balance between privacy and surveillance that no one, not even the industry at the center of the controversy, could have anticipated.”

Though he does not go on to outline those consequences, CALEA (as well as its limitations in the face of encrypted technology) loomed large in cases like the FBI’s 2016 attempts to compel Apple to unlock the phone of a gunman involved in a mass shooting in San Bernardino, Calif. It would have been fascinating to read Hochman’s analysis of how CALEA’s provisions intersected with this case, but as he writes in the opening line of his epilogue, “Our story ends in 2001.”

Hochman spends only about a page in the epilogue outlining the Patriot Act and surveillance capitalism since 2001. He quickly retrains his attention on his true subject: wiretapping. “The good old-fashioned wiretap continues to thrive in American law enforcement” today, he writes. The use of wiretaps under Title III is apparently more than three times higher than it was in the 1980s and ’90s. Police continue to surveil communities of color extensively and to marshal resources toward surveilling drug operations specifically: As of 2014, nearly 90 percent of the wiretap work in the United States was drug-related. Hochman adds that today, debates about wiretapping happen largely “on the margins” or in the wake of scandals like the 2013 Edward Snowden leaks.

After decades of controversy, Hochman shows, the use of wiretaps became institutionalized in the 20th century. But he only scratches the surface of how private companies in more recent decades, enjoying a lax regulatory environment, have encoded surveillance tracking into the structure of apps as well as the Internet itself.

We are now living in the world that the wiretap (and the chaotic, inconsistent legal responses to it) built. In recent years, surveillance technology has once again evolved faster than regulations. Congress has yet to pass comprehensive privacy legislation to regulate how apps collect user location data, leaving corporations free to monetize your every move and federal agencies free to track immigrants.

In a passage about phone bugging in the 1950s and ’60s, Hochman writes: “The ambiguity of the law made state and federal officials much less equipped to keep pace with the developments that ensued.” The same can still be said today.