It’s easy to dismiss a movie you don’t enjoy as boring. But what I learned from this Romanian ultrarealist film is that there are two completely distinct types of boredom at the movies. The first is the boredom of an eye-roll-inducingly dumb treasure chest of Hollywood clichés — Transformers, say, or Fool’s Gold. The second is the boredom of a movie that aspires to be exactly as boring as the real life people go to movies to escape.

Such is Corneliu Porumboiu’s film Police, Adjective, which has earned widespread critical praise and screened at Cannes. Make no mistake: This movie is dull. It follows a young cop, Cristi (Dragos Bucur), as he works the least exciting narcotics case imaginable, trailing a teenager who appears to be committing the grave crime of smoking hashish and sharing it with friends. By the time Cristi has finished surveilling an apartment complex, you will have memorized the graffiti on the wall. Porumboiu shoots the movie in long takes, most of them from a distance. Though it isn’t quite in real time, it feels that way.

But this kind of boredom — the soul-crushing boredom of experiencing someone else’s tedium for a change — can do strange things to a movie-goer. When something finally happens in the film, it may elate you.

For me, that happened in the scene where Cristi’s wife (Irina Saulescu) keeps replaying a syrupy pop ballad on YouTube. She plays it once, twice, three times — two of which we hear in their entirety — while her husband huddles in their tiny kitchen, eating his dinner alone and clearly wondering how things went downhill so quickly after their honeymoon. Meanwhile, the ballad uses a hundred hackneyed metaphors to extol the joys of everlasting love. Finally, Cristi tells his wife he doesn’t understand the song. And that’s when it becomes clear that Police, Adjective is about something.

It’s actually about plenty — mainly about tricky words and state-sponsored injustice, and how they combine to keep people from doing what they know to be right. Because Romania is no longer a closed dictatorship, Cristi has visited freewheeling places such as Prague, where he saw people smoking hash on the street with impunity. Yet his superior expects him to arrest a teenager on the mere suspicion of trafficking — a crime that could land the boy in jail for three to seven years. Reluctant and frustrated, Cristi draws out the investigation as long as he can. But in the end, he has to face the Boss.

The Boss is played by Vlad Ivanov, who was the scary abortionist in 4 Months, 3 Weeks and 2 Days. In that movie, he coldly lectured two hapless students about breaking the law even as he helped them do it. In this one, he continues his reign of terror over unruly Romanian youth by giving Cristi a lesson in the dictionary meanings of words like “law” and “conscience.” Yes, the climax of this film involves a guy reading from the dictionary.

And it’s mesmerizing. In its own small, painstaking way, Police, Adjective is dramatizing the same clash between inflexible institutions and people, between no-tolerance drug policy and reality, that we see played out on an expansive American stage in “The Wire.” It also offers insight into the mundane workings of a state still emerging from totalitarianism.

And finally, yes, the film is a decent cure for insomnia. Yet it’s the long stretches of nothing happening — just like life — that give the final scene its impact. This may not count as a recommendation, but if you can stay awake, you’ll be glad you did.