How many federal prison years are being served by defendants who (plausibly?) claimed compliance with state medical marijuana regimes?

The question in the title of this post is prompted by this new article from Michigan headlined "West Michigan man sent to prison for purported medical marijuana grow operation."  Here are the basics of this story with some follow-up data/questions:

One of the two leaders of a medical marijuana grow operation has been sentenced to 14 years in federal prison.  Phillip Joseph Walsh, 54, was sentenced Monday by U.S. District Judge Paul Maloney in Kalamazoo.  Betty Jenkins, described as his "life partner" in court records, will be sentenced June 29.

The Kent County residents were convicted at trial of running a marijuana grow operation that prosecutors say brought in $1.3 million.  The two, along with eight others, including a doctor who authorized patients for use of medical marijuana, were arrested last year for growing marijuana in multiple places in West Michigan.

The government contended that much of the marijuana grown was sold outside of Michigan. Jenkins was considered the leader of the organization.  The defendants argued they acted within the guidelines of Michigan's medical marijuana law but were not allowed to use the law as a defense to the federal charges.

Kent County Area Narcotics Team and U.S. Drug Enforcement Administration used multiple search warrants to raid numerous properties, including apartment buildings in Gaines Township. Police seized 467 marijuana plants and 18 pounds of processed marijuana.

Defense attorney Joshua Covert said his client, a father of four daughters, was "very nervous" after reviewing advisory sentencing guidelines that called for 151 to 188 months in prison.  He said that Walsh has been a good, caring father and a hard worker and has led a productive life.  "Mr. Walsh and his life partner, Ms. Jenkins, lived a comfortable but certainly not lavish or extravagant life that was financed by rental income from property Ms. Jenkins obtained through her divorce," the attorney wrote in a sentencing memorandum.

"The endeavor of manufacturing marijuana was not particularly successful for Mr. Walsh from a financial standpoint because it proved to be difficult and expensive to manufacture marijuana," he wrote....  He said his client "is not seeking sympathy or pity" but asked for leniency "given the relaxed attitude toward marijuana nationwide and specifically Michigan in regards to marijuana."

Assistant U.S. Attorney Mark Courtade said Walsh and Jenkins began manufacturing marijuana on Forest Hill Avenue SE in 2010.  Walsh hired a man to help with the grow operation before both were convicted for their roles.  The other man quit, "but Walsh and Jenkins carried on, unfazed," Courtade said.

"Defendant Walsh developed the 'marketing scheme' that ensnared many of the codefendants in this case," the prosecutor wrote....  He said that Walsh tried to insulate himself by staying he was only "'building grow rooms' ... his real motivation was far more nefarious."

He said Walsh grew marijuana for profit, with some sold in Ohio, some in Rhode Island. Courtade also said that Walsh could not document wages he earned — he reported remodeling and roofing homes — but he managed to hired his own attorneys, pay for a co-defendant's expert witnesses and build numerous manufacturing operations. He recommended a sentence within guidelines.

This story of a lengthy federal prison sentence for major marijuana dealing in a medical marijuana state itself highlights the challenges of coming up with a satisfactory answer to the question in the title of this post.  The defendants here were apparently quick to claim that they were acting in accord with Michigan state medical marijuana laws, but the facts reported suggest little basis for this defense claim of state-law compliance.

That said, I know there are at least a handful (and perhaps more than a handful) of the roughly 5000 federal prosecutions for marijuana trafficking sentenced in federal courts each year involving defendants who truly have a plausible claim to being in compliance with state medical marijuana laws.  A low "guestimate" that an average of 10 federal marijuana defendants in each of the last 10 years have been been sentenced to an average of 10 years in federal prison for medical marijuana activities would, in turn, suggest that 1000 years in federal prison are being served by defendants who plausibly claimed compliance with state medical marijuana regimes.  

That is a lot of federal prison time (which would be costing federal taxpayers roughly $30 million because each prison year costs roughly $30,000).  And I have an inkling the number could be higher.