
    Locke v. New Orleans.
    1. A statute -which simply authorizes the imposition of a tax according to a previous assessment is not retrospective.
    2. Every retrospective act is not necessarily an ex post facto law.
    3. Such laws embrace only such as impose or affect penalties or forfeitures.
    The legislature of Louisiana enacted, A.D. 1850—
    
      “ That each of the municipalities of said city shall be and is hereby empowered to levy a tax on capital on the assessment roll for the year 1848, and a tax on capital on the assessment roll for the year 1849: Provided, that the taxes on capital on said assessment rolls, for the years 1848 and 1849, shall not exceed the amounts already imposed by existing ordinances of the said municipalities.”
    Under the authority of this act the City of New Orleans, having levied a tax on capital owned and employed during the years mentioned by Locke, brought suit to enforce its payment. One defence set up was that the act was unconstitutional. The Supreme Court of the State having, on appeal from the District Court, whose judgment it affirmed, decided that it was not, the case was now brought here for review.
    
      Mr. Janin for the 'plaintiff in error. No opposite counsel.
    
   Mr. Justice FIELD

delivered the opinion of the court.

The legislature of Louisiana in 1850 passed an act authorizing each of the municipalities of the City of Hew Orleans to levy a tax on capital within its limits on the assessment rolls of 1848 and 1849, not to exceed the amounts imposed by existing ordinances. The present action was instituted to recover, in part, the amount of the tax levied under this act upon capital owned and employed by the defendant in one of the municipalities. As a defence the defendant, among other things, alleged the unconstitutionality of the act of the legislature authorizing the tax. The District Court, in which the action was brought, gave judgment for the city, and the Supreme Court of the State affirmed the judgment.

The unconstitutionality of the act was asserted from its supposed retroactive operation, upon the notion that the prohibition of the Federal Constitution upon the States to pass an ex post facto law extended to all retrospective laws.

There was nothing in the position taken which entitled it to consideration. In the first place the act was not subject to the imputation of being retrospective. . It did not operate upon the past, or deprive the party of auy vested rights. It simply authorized the imposition of a tax according to a previous assessment. In the second place, even if the law had been strictly retrospective, it would not have been within the constitutional inhibition. JEx post facto laws embrace only such as impose or affect penalties or forfeitures; they do not include statutes having any other operation. The term ex post facto, literally construed, would apply to any act operating upon a previous fact, yet the restricted sense stated is the one in which it has always been held. It was the sense in which it was understood at the time the Constitution was adopted, both in this country and in England.

Judgment aeeirmed. 
      
       1 Blackstone, 46; Calder v. Bull, 3 Dallas, 390.
     