Popping the drug molly could land a disgraced NYPD officer in a federal lockup.

Merlin Alston, 34, faces narcotics conspiracy charges for his alleged role helping, driving, and protecting a drug dealer for four years.

To make their case for Alston’s role in a drug conspiracy, prosecutors from Manhattan U.S. Attorney Preet Bharara’s office will argue he was tight with other dealers, according to court papers.

Alston, who is suspended, went clubbing with the dealers in New York and also traveled with them to Atlantic City and Miami, prosecutors say.

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While partying, Alston worked to earn dealers’ trust, “including by occasionally using the drug molly, and getting in fights,” prosecutors said.

The feds will also argue Alston’s apparent preference for the drug shows he knew dealing was taking place around him.

Alston’s lawyers had unsuccessfully fought prosecutors’ push to bring his alleged drug use up in court, arguing that clubbing and fighting, as well as ingesting molly, aren’t evidence of conspiracy.

But Manhattan Federal Judge Colleen McMahon agreed with prosecutors — and said Alston’s alleged molly use could show he was aware of a drug conspiracy.

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The fact Alston got molly from a cooperating witness and took it with him “tends to show that the defendant knew” the cooperator was distributing the euphoria-inducing stimulant, McMahon wrote.

In addition, Alston’s bail was recently revoked after a key witness in his upcoming trial, Robert Bishun, was found strangled and stuffed in the back of a BMW.

Alston’s lawyer, Jeffery Greco, said McMahon's opinion "simply does not make concrete sense.”

The reasoning, he said, “is as illogical as reasoning that one who eats Girl Scout cookies must they, themselves, be a Girl Scout.”

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“That is akin to saying that everyone who buys or uses illicit drugs recreationally is part of a drug cartel, or drug conspiracy simply because they helped consume the drugs that were being sold, and were therefore a cog in the wheel of narcotics trafficking,” he added.