OPINION

delivered the opinion for a unanimous Court.

In this case, the court of appeals addressed the merits of appellant’s appeal from the trial court’s post-judgment order denying appellant’s request for a time credit on his 180-day incarceration in a county jail as a condition of his community supervision.1 We decide that the court of appeals should have dismissed the appeal for lack of jurisdiction.

Appellant was convicted of indecency with a child and received a twenty-year prison sentence, which appellant began serving on May 25, 2005. On June 7, 2006, this prison sentence was overturned on direct appeal, with a new punishment hearing ordered. By June 4, 2007, appellant had been returned to the Ellis County jail from prison at which time he was released on bond pending the new punishment hearing.2 See Abbott, 245 S.W.3d at 20. At the new punishment hearing on August 16, 2007, a jury sentenced appellant to ten years in prison on the indecency conviction and recommended that this sentence “be suspended subject to community supervision.”

The trial court’s judgment, dated August 16, 2007, “adjudged [appellant] guilty” of the indecency offense and ordered that appellant be placed on community supervision for ten years commencing on that day “subject to the conditions of supervision imposed by the Court and served on the Defendant.” This judgment also recites that appellant’s sentence was imposed on August 16, 2007. The trial court signed another order on August 16, 2007, setting out the conditions of appellant’s community supervision. One of these conditions required appellant to “[rjemain under custodial supervision and serve 180 days in the Ellis County Wayne McCollum Detention Center” beginning on August 18, 2007.3 This condition further recited that appellant “shall be credited with 0 days” on this 180-day incarceration.

On August 24, 2007, appellant fried a motion in the trial court seeking a time credit on this 180 days for the approximately two years of his “previous confinement time.” 4 The State’s response to this motion asserted that appellant is not entitled to any credit on this 180 days, because, as a condition of appellant’s com*696munity supervision, this 180 days is not considered part of appellant’s sentence for purposes of Article 42.03, § 3.5 The State’s response further asserted that appellant will be entitled to this credit if “his community supervision is revoked and he is ordered to serve a prison sentence.” The State’s response asserted:

In this case, Defendant was originally sentenced within the allowable range of punishment. He has not been penalized for filing an appeal. The time he served in prison will be credited when his community supervision is revoked and he is ordered to serve a prison sentence. In fact, one must wonder whether Defendant will, should his request for credit toward the condition of community supervision be granted now, argue upon revocation that the time he previously served in prison should also count toward his sentence. Just as Defendant will not be entitled to time toward his sentence for the time he will serve as a condition of community supervision, he is not now entitled to the reverse. This Court has not abused its discretion in declining to grant Defendant time credit toward his condition of community supervision.

On September 7, 2007, the trial court signed an order denying appellant’s time-credit motion. On Tuesday, September 18, 2007, appellant filed a notice of appeal from this order (the clerk’s file-stamp indicates that this notice of appeal was filed on September 18, 2007, at 2:45 p.m., while the certificate of service on the notice of appeal indicates that it was sent to opposing counsel on September 17, 2007).6

The court of appeals, with one justice dissenting, decided that it had jurisdiction to consider the merits of appellant’s appeal and that the trial court should have granted appellant credit for the time previously served. See Abbott, 245 S.W.3d at 20-23.7 We granted review. The grounds upon which we granted review present the following issues:

1. Did the Tenth Court of Appeals have jurisdiction to consider an appeal from the order denying time credit?

2. Did the Tenth Court of Appeals err in determining that the trial court was without discretion to deny credit for the time served on the original sentence toward the days ordered as a condition of community supervision after retrial?

The court of appeals decided that it had jurisdiction to decide the merits of appellant’s appeal from the trial court’s post-judgment order denying his time-credit motion, because there was no “statute or rule precluding” the appeal. See Abbott, 245 S.W.3d at 20. This, however, is not the standard for determining jurisdiction. The standard for determining ju-*697risdietion is not whether the appeal is precluded by law, but whether the appeal is authorized by law. See Tex. Const, art. V, § 6(a), (providing that courts of appeals “shall have appellate jurisdiction co-extensive with the limits of their respective districts, which shall extend to all cases of which the District Courts or County Courts have original or appellate jurisdiction, under such restrictions and regulations as may be prescribed by law” and “[sjaid courts shall have such other jurisdiction, original and appellate, as may be prescribed by law”); Article 44.02, Tex. Code Crim. Pkoc., (“[a] defendant in any criminal action has the right of appeal under the rules hereinafter prescribed”); Tex.R.App. Proc. 25.2(a)(2) (a defendant “has the right of appeal under Code of Criminal Procedure article 44.02 and these rules” in every case in which the trial court “enters a judgment of guilt or other ap-pealable order”); McIntosh v. State, 110 S.W.3d 51, 52 (Tex.App.-Waco 2002, no pet.) (a defendant has right to appeal from a final judgment of conviction or when “expressly granted by law”) (internal quotes omitted); Abbott, 245 S.W.3d at 23 (Gray, J., dissenting) (courts of appeals have no appellate jurisdiction in criminal matters “absent a specific authorization by law”).8

In this case, we have not found any rule or any statutory or constitutional provision that would authorize appellant’s appeal from the trial court’s post-judgment order denying his time-credit motion. See Staley v. State, 233 S.W.3d 337, 338 (Tex. Cr.App. 2007) (dismissing the defendant’s appeal because it was not authorized by law). The court of appeals, therefore, lacked jurisdiction to decide the merits of appellant’s appeal. See id.; Abbott, 245 S.W.3d at 23 (Gray. J., dissenting).9

The judgment of the court of appeals is reversed, and the case is remanded there for further proceedings consistent with this opinion.

concurring.

I join the opinion of the Court. I write separately, however, to emphasize that, had appellant timely appealed from the trial court’s August 16, 2007, judgment placing him on community supeivision, he would have had a valid claim against the trial court’s decision to require, as a condition of community supervision, that he serve 180 days in jail without receiving time credit for the 740 days he had already *698spent in prison awaiting the outcome of his appeal.

A condition of community supervision, to be valid, must have a reasonable relationship to the rehabilitation of the accused, the compensation of the victim, or the protection of the public. See Tamez v. State, 534 S.W.2d 686, 691 (Tex.Crim.App. 1976). In light of the very lengthy post-judgment incarceration endured by appellant in this case, it was unreasonable for the trial court to require him to serve an additional 180 days in jail as a condition of community supervision. It is inconceivable that such further incarceration would have had any reasonable relationship to appellant’s rehabilitation or to the protection of the public.

In addition, the United States Supreme Court has held that the Fifth Amendment protection against double jeopardy is violated whenever punishment already endured for an offense is not fully subtracted from any new punishment imposed. North Carolina v. Pearce, 395 U.S. 711, 718, 89 S.Ct. 2089, 23 L.Ed.2d 656 (1969). In my view, that crediting principle applies with equal force to the probation condition in question — really, a new type of punishment — imposed for the same conviction after appeal.

Finally, I agree with the court of appeals that “denial of time credit [in a situation like the one here] would have the effect of penalizing a defendant [for] prosecuting his appeal, and a defendant should not have to ‘start over’ ” once he is correctly sentenced. Abbott v. State, 245 S.W.3d 19, 22 (Tex.App.-Waco 2007) (quoting Watson v. State, 942 S.W.2d 723 (Tex.App.-Houston [14th Dist.] 1997, no pet.)).