Once, a senior associate for whom I was working berated me for such a mistake and said, “Getting these things right is the easy part, and if you can’t get that right, what does it say about your ability to analyze the law properly?” I learned my lesson. To restore the focus-training function of the classroom, I stopped allowing laptops in class early in my teaching career. Since then research has confirmed the wisdom of my choice.

Focus is crucial, and we do best when monotasking: Even disruptions of a few seconds can derail one’s train of thought. Students process information better when they take notes — they don’t just transcribe, as they do with laptops, but they think and record those thoughts. One study found that laptops or tablets consistently undermine exam performance by 1.7 percent (a significant difference in the context of the study). Other studies reveal that writing by hand helps memory retention. Screens block us from connecting, whether at dinner or in a classroom. Kelly McGonigal, a psychologist and lecturer at Stanford University, says that just having a phone on a table during a meal “is sufficiently distracting to reduce empathy and rapport between two people.”

For all these reasons, starting with smaller classes, I banned laptops, and it improved the students’ engagement. With constant eye contact, I could see and feel when they understood me, and when they did not. Energized by the connection, we moved faster, further and deeper into the material. I broadened my rule to include one of my large upper-level courses. The pushback was real: A week before class, I posted the syllabus, which announced my policy. Two students wrote me to ask if I would reconsider, and dropped the class when I refused. But more important, after my class ends, many students continue to take notes by hand even when it’s not required.

Putting aside medical exemptions, many students are just resistant. They are used to typing and prefer it to writing. They may feel they take better notes by keyboard. They may feel they know how to take notes by hand but do not want to have to do so. They can look up material, and there’s no need to print assignments. Some may have terrible handwriting, or find it uncomfortable or even painful to write.

To them, I’ll let the Rolling Stones answer: You can’t always get what you want, but sometimes you get what you need. My students need to learn how to be lawyers and professionals. To succeed they must internalize an ethos of caution, care and respect. To instill these values and skills in my students, I have no choice but to limit laptop use in the classroom.