Substantively unreasonable harsh sentences do exist---at least in the Eighth Circuit.*
In United States v. Martinez, the district court sentenced Mr. Martinez to 262 months' imprisonment for possessing 50+ grams of methamphetamine with intent to distribute. This was a guideline sentence, assuming that Mr. Martinez was a career-offender under the residual clause because of a prior escape conviction. This assumption was wrong, as the government later conceded, but the district court also stated on the record that even if Mr. Martinez was "technically" not a career offender, the court would impose the same sentence as an upward variance. The court justified this alternative sentence on grounds that Mr. Martinez had been convicted 6 years earlier at age 18 on a state gun charge for a gang-related non-injury drive-by shooting; his escape had occurred during an arrest for failing to appear on the gun charge; and the government had presented evidence of more recent local gang ties at his federal sentencing.
On appeal, the Eighth Circuit held that the district court's alternative sentence was "substantively unreasonable":
First, Martinez’s convictions do not warrant such a severe upward variance. Martinez’s two convictions undoubtedly demonstrate serious, violent behavior, but the guideline range already accounted for these prior convictions, each of which received three criminal history points. . . .
Second, the evidence the government presented relating to Martinez’s gang ties does not justify a nine-year upward variance either. The government presented evidence Martinez appeared in music videos along with other members of the East Side Locos prior to his incarceration. He also appeared with other East Side Locos gang members in photographs. While these photos and videos show Martinez’s gang ties, they do not depict Martinez actively engaging in any violent behavior. And, more importantly, they do not depict such egregious, violent behavior that they warrant the substantial upward variance the district court imposed.
The Eighth Circuit cited Gall v. United States for the proposition that a major variance such as was imposed here should be supported by a more significant justification than a minor one. But of course, the raw facts are the same regardless of whether Mr. Martinez was "technically" a career offender or not. Whether viewed as a guideline sentence or a variance, this punishment did not fit the crime.
*Their existence in the Tenth Circuit is questionable. That Court has at least twice labeled lenient sentences substantively unreasonable, but has never, to this writer's knowledge, concluded that a harsh sentence was substantively unreasonable.