Ariana Madix's brother Jeremy is in major trouble with the law ... police say he and an accomplice were busted with suitcases filled with over 100 pounds of marijuana.

According to court documents, obtained by TMZ ...  Jeremy Madix – who has appeared on "Vanderpump Rules" with his famous sis – and Jonah Ahad were scheduled to board a February 16 flight to Frankfurt, Germany, from Orlando International Airport in Florida.

But, the dudes never got past the security checkpoint. The docs say Customs and Border Protection agents searched the pair's three suitcases – two of which belonged to Madix -- and were loaded with ganja. In fact, police say Madix's suitcases contained a total of 64 bags of pot weighing a whopping 76 pounds.

In Ahad's suitcase, cops say they discovered 31 bags of weed weighing 37 pounds.

When detectives tried to question the two, Madix and Ahad refused to talk without their attorneys present, the docs say.

Strangely, both men were not arrested on the spot in February -- and we're trying to find out why from the Orlando Police Department.

However, they were eventually booked on arrest warrants and charged with felony trafficking in cannabis. Ahad was busted in May and Madix was taken into custody last Tuesday.

We've reached out to Ariana's camp, but no word back.