these convictions in the ultimate computation of Brown’s sentence. Three points are added for each prior sentence of imprisonment exceeding one year and one month. There is no limit to the number of points that may be counted under this item.... A sentence imposed more than fifteen years prior to the defendant's commencement of the instant offense is not counted unless the defendant's incarceration extended into this fifteen year period. Brown has made no assertion that either his 1981 conviction or his 1985 conviction is invalid. It is incumbent upon the defendant to prove the invalidity of any prior convictions to prevent their use in the computation of criminal history. See U.S. v. Hoffman, 982 F.2d 187 (6th Cir.1992); also see United States v. Canales, 960 F.2d 1311 (5th Cir.1992) (<HOLDING>). This court thus finds here that the
holding that the defendant failed to carry his burden of proving the invalidity of the waivers of counsel for prior colorado convictions holding that a defendant may challenge the validity of prior convictions during a sentencing hearing and that the burden to establish invalidity is on the challenging party holding that when a defendant admits prior convictions at a habitual offender hearing he waives any complaints about the validity of the prior convictions holding that the burden is on the defendant when the validity of the warrant is challenged holding that the burden is on the plaintiff