political maverick and self-described independent thinker during his four terms in the U.S. Senate, Joe Lieberman is now demonstrating that he also follows his own path in matters of religion.

Lieberman has come out with a book geared for use during Pesach, but unlike most books for the holiday, which are designed to be used at the first seder, his is meant to be read on the second night — at the very end of the seder.

“With Liberty and Justice: The Fifty-Day Journey from Egypt to Sinai” (Maggid/OU Press) is a collection of 50 philosophical essays that coincide with the Omer, the traditional “counting of the days” between the second night of Passover and Shavuot; the period, which lasts for seven weeks, is marked by a sense of heightened mindfulness during which a prayer is recited each evening. Shavuot marks God’s giving the Torah — the foundation of the Jewish legal system — to the Children of Israel at Mount Sinai.

The book’s short essays — most run from two to four pages — reflect the sense of justice that earned Lieberman the unofficial title of “The Conscience of the Senate.” They contain his thoughts on secular and Jewish law, public service and religious obligation, and his experiences as a politician in Connecticut and Washington. Lieberman, who famously left the Democratic Party late in his career to become an Independent, touches on such issues as civil rights, environmental protection and LGBT rights, all in a biblical context, paying special attention to the Ten Commandments.

In other words, in 165 pages he deals with the issues that motivated him to enter politics for the first time almost 50 years ago. His career has always been guided by his religious beliefs; after his terms as a state senator and then attorney general for the state of Connecticut, he was the first Orthodox member of the United States Senate and, as Al Gore’s running mate on the Democratic ticket in 2000, the first Jewish politician to be nominated by a major political party as vice president. “I’ve spent my life in the law,” he said, explaining how his book explores the intersection between the lower-case use of the term and its upper-case religious use.

“You don’t have to be a lawyer to serve God according to those laws and values,” he writes on Day 1. “I write as a layperson, not a rabbi, which means I have less authority but more latitude. Most of all I write as a committed believer in Judaism who loves Shavuot, the Law and the law.”

Lieberman, who attended public school and Hebrew school while growing up and later educated himself about Judaism through extensive reading, said the intensive study he did for the book added to his understanding of the relationship between God and man, and the role that the mitzvot play in daily life.

“I saw some things in the text [of the Torah and commentaries] I had not seen before.”

“I saw some things in the text [of the Torah and commentaries] I had not seen before,” he said, sitting in his office at Kasowitz Benson Torres law firm in Midtown. “I started to look at text in a different way.”

On the walls and shelves of his office are mementoes of his political past and Jewish involvements: awards from various organizations and governments; busts of Churchill and JFK; an Electoral College tally of the contested 2000 race; photos of the senator with presidents; and family photos, a Koren Siddur and an English translation of the Book of Isaiah.

Lieberman, who left the Senate in 2013, spends half his time “lawyering” and some time teaching at Yeshiva University, while keeping his promise to his wife, Hadassah, that in his putative retirement he would maintain a less intense schedule than he did in the Senate. (After President Trump fired FBI Director James Comey, Lieberman was thought to be a leading candidate for the agency’s top job.)

But he’s still busy at 76. “I have a compulsive side to me,” he said. “By nature, I continue to work.”

“With Liberty and Justice” draws on his life drafting laws (in the Senate) and enforcing them (in his earlier position as attorney general in Connecticut).

It all started at Sinai, he said.

Accepting the Torah was a “precondition” for the Jewish people’s earning the right to enter the Promised Land, Lieberman, said. “The nation got its values before it got its land.”

“Freedom is not enough,” he said; his reference is to the slavery in ancient Egypt but applies to the constant relationship between personal autonomy and obedience to national law.

The lessons of the Passover-to-Shavuot period transcend time or place, Lieberman writes in his Day 50 entry. “A question raised in France in the 1200s might have been answered in Spain one hundred years later. A rabbi living in Yemen felt perfectly at home reading an Eastern European gloss of the Talmud. Today, a question of Jewish law raised over the internet by a student in Detroit, for example, will be answered within minutes just as easily by people from the United States, or Israel, or South Africa.”

Though the book is a serious one, Lieberman writes with a dry, well-honed sense of humor. About the tradition of eating dairy on Shavuot, he quips: “As a long-time legislator, who heard appeals for help from various economic interest groups, I once imagined that the custom was the brainchild of an Association of Jewish Dairy Farmers who complained to the rabbis that it was unfair that on the Sabbath and all of the Jewish holidays the custom was to eat meat. Couldn’t at least one holiday feature dairy products?”

Lieberman’s book is a pitch for Shavuot. “It’s where the law began.” He writes that he wrote the book “with the objective of turning the observance of the Passover Seder from a one-night experience into a seven-week journey of study that culminates in the celebration of Shavuot.”

“I believe that Shavuot is the most under-appreciated holiday on the Jewish calendar.”

“I believe that Shavuot is the most under-appreciated holiday on the Jewish calendar,”  he said.

The book, his eighth, grew out of a conversation with Rabbi Menachem Genack, general editor of the OU Press. Rabbi Genack had suggested to Lieberman the subject of his earlier book, “The Gift of Rest: Rediscovering the Beauty of the Sabbath” (Howard Books, 2012), which extolls the virtues of keeping a biblically commanded day of rest.

Then Rabbi Genack proposed that Lieberman write a book about Pesach. “The last things the world needs,” Lieberman answered, “is another book about Passover.” Instead, he’d write about Shavuot.

Rabbi Genack suggested that Lieberman, who once considered a career in journalism, write the book in partnership with Rabbi Ari Kahn, who was ordained by Yeshiva University, serves as director of Foreign Student Programs there, and is a senior lecturer in Jewish studies at Bar-Ilan University in Israel.

Inspired by the Torah portion commentaries of Rabbi Jonathan Sacks, former chief rabbi of England, Lieberman said he decided to structure his book as a series of essays to be read day-by-day, instead of week-by-week.

This year, as he regularly does, Lieberman will religiously count the Omer, starting on the second night of Pesach, and celebrate Shavuot with his family, he said.

If his book is successful, he said, more members of the Jewish community will do the same thing. “I hope it leads more people to observe Shavuot.”