The full scope of Jewish texts and traditions couldn't help the rabbi sort this one out: Could he skate to synagogue on the holy day of rest and prayer?

Dov Kaplan decided he should go straight to the top for an answer -- a religious sage in Jerusalem who rules on what's acceptable, and what's not, under Orthodox Jewish law. His verdict on the in-line skates? Roll on, including Saturdays.

The recent case was more than just a quirky display of Torah scholarship.

The modern world of gadgets and hobbies makes being true to faith increasingly difficult for Jews who strictly observe Shabbat, or the Sabbath, and its detailed list of forbidden activities. The ban includes any type of commercial labor, nearly all modes of transportation and anything construed as igniting or extinguishing "fire," such as cooking or even flicking a light switch.

Any Shabbat problem -- like the roller-skating question -- probably will find its way to a crammed wedge of offices on a Jerusalem hilltop. The space serves as a kind of one-stop answer factory: the staff responding to letters and e-mails, the head rabbi issuing religious decrees and amateur inventors tinkering at work tables to find Shabbat-acceptable devices. Among the latest projects is a doorbell that uses air pressure instead of electricity.

"We believe the Torah is a living document and needs to address modern issues, especially with the incredible pace of change," said Rabbi Levi Yitzchak Halperin, who directs the Institute for Science and Halacha, Halacha being the body of Jewish law. "But we are not an institute that is looking for loopholes."

On roller-skating? "That wasn't a real hard one," he said with a smile.

Kaplan's problem arose after plans were made for a second synagogue in Caesarea, a town of 5,000 people on the Mediterranean coast that has the feeling of a Florida resort, right down to bike paths and an 18-hole golf course.

Cars are out on Shabbat. Bicycles are banned because of the risk of fixing a chain or flat, which would be considered work. So Kaplan thought of zipping between the two synagogues using in-line skates -- even though he needs beginner-level lessons.

"We must have respect for Jewish law and traditions," said Kaplan, 45, who was raised in Long Beach, N.Y., and immigrated to Israel when he was 11."But we also have to show that Orthodox rabbis are not distant, unapproachable and closed to new ideas. Who knows if I'll actually skate. It's more about making a point."

Halperin saw no problem. He decided that skates can't break down the way bikes do.

The institute is a mix of library, workshop and warehouse. In one room, Orthodox rabbinical students pore over books. Next door is a workshop loaded with switches and wires, a place to experiment with ways around using electricity on Shabbat. Other Jewish groups in Israel and abroad also offer guidance on Shabbat and other matters, but Halperin is widely considered the definitive voice.

When the institute opened in the 1960s, electricity was the main source of inquiries and innovations -- which some ultra-Orthodox dismissed as diluting Jewish law. About a third of Israel's Jewish population either strictly adheres to Shabbat codes or follows them to some degree, such as not watching television on the holy day but traveling by car to synagogue. In the United States, about 7 percent of Jews identify themselves as Orthodox.

Under Orthodox views, it's forbidden to "close" an electrical circuit on Shabbat -- for example turning on a light, dialing a phone or hitting an elevator button.

The solution was developing appliances, phones and other electrical devices with preset open-and-close cycles. The institute's Shabbat phone is a prime example: It has a constant "on-off" cycle so the caller is not directly dialing a number, but allowing the phone to make the connection.

It's no longer so straightforward. Halperin is peppered with requests of all kinds.

Can the institute develop a TV remote for Shabbat? Not interested in even trying.

Is stem cell research acceptable? Yes, Halperin says, as long as the process will not alter the genetic makeup of the patient. Cloning, however, is considered wrong.

The use of sperm banks? There are many obstacles, Halperin says. But in some cases -- such as a husband who froze his sperm before he died or was rendered sterile -- it's allowable because reproduction remains within the family.

The queries have even reached beyond this world.

Shabbat questions about space travel were raised when Israeli astronaut Ilan Ramon was aboard the space shuttle Columbia, which broke apart during reentry in 2003. When, it was asked, is Shabbat in outer space, given that the observance begins and ends with sunset? Halperin's conclusion: Calculate when Shabbat would occur at the launch pad.

Other solutions require a bit more elbow grease. One of them was tucked into a corner: an attempt to create Shabbat wheelchair that uses pneumatic power as an alternative to electric power. There are still some bugs, said the institute's key researcher, Rabbi Shmuel Strauss.

"It still doesn't have the efficiency of a battery," Stauss said. "We're working on it."

Rabbi Levy Itzchak Halparin, who directs the Institute for Science and Halacha in Jerusalem, tackles a wide range of questions about what's acceptable, and what's not, under Orthodox Jewish law.