firearms-regulation

65 cases — ← All topics

Case Title Lower Court Docketed Status Flags Tags Question Presented
25-6761 Kennan Alexis v. United States Fifth Circuit 2026-02-10 Denied Response WaivedIFP constitutional-challenge felony-possession firearms-regulation non-violent-drug-offense second-amendment statutory-interpretation Whether 18 U.S.C. § 922(g)(1) violates the Second Amendment either facially or as applied to individuals who, like Petitioner, only have felony convic…
25-6711 Matthew Harris England v. United States Fourth Circuit 2026-02-04 Denied Response WaivedIFP bruen-standard dangerous-and-unusual firearms-regulation law-abiding-citizens second-amendment text-and-history In New York State Rifle & Pistol Ass'n v. Bruen, 597 U.S. 1 (2022), this Court adopted a two-step text-and-history standard for analyzing whether laws…
25-6682 Fidel Aramboles v. United States Second Circuit 2026-01-30 Denied Response WaivedIFP bruen-precedent constitutional-rights criminal-law felony-possession firearms-regulation second-amendment 18 U.S.C. § 922(g)(1) imposes a lifelong prohibition, punishable by up to 15 years' imprisonment, on the possession of any firearm or ammunition, for …
25-6598 Ashley Moore v. United States Fifth Circuit 2026-01-15 Denied Response WaivedIFP bruen-rahimi-test commerce-clause firearms-regulation historical-analysis probation-status second-amendment 1. Whether an individual's probation or supervised release status categorically strips them of Second Amendment protection under 18 U.S.C. § 922(g)(1)…
25-6513 Alexander Jon Ogilvie v. United States Tenth Circuit 2026-01-07 Denied Response WaivedIFP constitutional-rights criminal-indictment firearms-regulation gun-possession second-amendment statutory-interpretation Whether 18 U.S.C. 922(n), the federal statute that prohibits those under indictment from shipping, transporting, or receiving any firearm or ammunitio…
25-6468 Derrick Hahn v. United States Fifth Circuit 2026-01-02 Denied Response WaivedIFP commerce-clause constitutional-rights criminal-law firearms-regulation second-amendment statutory-interpretation 1. Whether 18 U.S.C. § 922(g)(1) violates the Second Amendment when applied to an individual based on his past conviction for a non-violent offense. …
25-6460 Brad O'Neal Lee v. United States Fifth Circuit 2025-12-31 Denied Response WaivedIFP constitutional-challenge felony-possession firearms-regulation legal-standing second-amendment statutory-interpretation Whether 18 U.S.C. § 922(g)(1) violates the Second Amendment on its face or as applied to Petitioner.
25-642 Lorenzo Garod Pierre v. United States Eleventh Circuit 2025-12-03 Denied Response Waived as-applied-challenge constitutional-law criminal-defendant firearms-regulation second-amendment statutory-interpretation Whether a criminal defendant may raise an as-applied Second Amendment challenge to 18 U.S.C. 922(g)(1).
25-6267 Alphonso Lataurean James v. United States Eleventh Circuit 2025-12-02 Denied IFP application-note constitutional-review criminal-conviction firearms-regulation second-amendment statutory-interpretation The questions presented for review are: (1) Is whether Application Note 14(b) unreasonably interprets the text of § 2K2.1(b)(6)(B), such that no defer…
25A607 Alexander Jon Ogilvie v. United States Tenth Circuit 2025-11-21 Presumed Complete constitutional-challenge criminal-law federal-public-defender firearms-regulation statutory-vagueness tenth-circuit Question not identified.
25-6153 Marco Antonio Sanchez v. United States Fifth Circuit 2025-11-18 Denied Response WaivedRelisted (2)IFP constitutional-challenge criminal-conviction due-process firearms-regulation second-amendment statutory-interpretation Below, Petitioner Marco Antonio Sanchez challenged the constitutionality of 18 U.S.C. § 922(g)(1), which makes it a crime for a person convicted of a …
25-6062 Carl Morgan v. United States Fifth Circuit 2025-11-07 Denied Response WaivedRelisted (3)IFP commerce-clause constitutional-rights criminal-law firearms-regulation second-amendment statutory-interpretation 1. Whether 18 U.S.C. § 922(g)(1) violates the Second Amendment when applied to individuals based on their past conviction for a non-violent offense. …
25-6054 Clyde Miller v. United States Second Circuit 2025-11-06 Denied Response WaivedRelisted (4)IFP appellate-procedure circuit-split constitutional-review firearms-regulation statutory-interpretation writ-of-certiorari Whether, because the Circuit Courts of Appeals and District Courts are split, a writ of certiorari should be granted to settle the Constitutionality o…
25-541 Benjamin Schoenthal, et al. v. Kwame Raoul, Attorney General of Illinois, et al. Seventh Circuit 2025-11-04 Denied Amici (3)Response RequestedResponse WaivedRelisted (4) citizens-rights constitutional-challenge firearms-regulation fourteenth-amendment public-transportation second-amendment Whether Illinois' flat ban on ordinary citizens carrying firearms on public transportation violates the Second and Fourteenth Amendments.
25-5867 James Bradley Vlha v. United States Ninth Circuit 2025-10-10 Denied Response WaivedIFP constitutional-challenge criminal-statute firearms-regulation gun-rights manufacturing-license second-amendment Whether the statute prohibiting manufacturing and dealing in firearms without a license, 18 U.S.C. § 922(a)(1)(A), is constitutional pursuant to the S…
25-5828 Joshua Devon Barrow v. United States Fifth Circuit 2025-10-08 Denied Response WaivedIFP bruen-rahimi-test commerce-clause firearms-regulation historical-analysis probation-status second-amendment 1. Whether an individual's probation or supervised release status categorically strips them of Second Amendment protection under 18 U.S.C. § 922(g)(1)…
25-421 National Association for Gun Rights, et al. v. Ned Lamont, in His Official Capacity as Governor of Connecticut, et al. Second Circuit 2025-10-07 Pending Amici (2)Relisted (7) common-use-test constitutional-interpretation firearms-regulation gun-rights heller-precedent second-amendment Whether a ban on the possession of AR-15-style rifles and firearm magazines with a capacity in excess of ten rounds—both of which are possessed by mil…
25-5758 Jerry Otis Moore v. United States Fifth Circuit 2025-09-30 Denied Response WaivedIFP circuit-split constitutional-rights felon-in-possession firearms-regulation second-amendment statutory-interpretation Does 18 U.S.C. § 922(g)(1) comply with the text and historical tradition of the Second Amendment in permanently disarming all felons, regardless of of…
25-5713 Emanuel Leyton Picon v. United States District of Columbia 2025-09-24 Pending IFP age-restriction constitutional-rights due-process firearms-regulation right-to-bear-arms second-amendment Whether the Second Amendment's guarantee of the right to keep and bear arms applies fully to 18-20-year-olds.
25-5678 Thomas Jarrell Shoffner v. United States Fourth Circuit 2025-09-18 Denied Response WaivedRelisted (6)IFP constitutional-challenge criminal-law district-court-procedure firearms-regulation motion-to-dismiss statutory-interpretation I. Whether the District Court Erred in Denying Appellant's Motion to Dismiss the Indictment on the Constitutionality of 18 U.S.C. § 922(g) (1).
25-5535 Jason Daniel Carbajal v. United States Fifth Circuit 2025-09-03 Denied Relisted (4)IFP constitutional-challenge criminal-conviction due-process firearms-regulation second-amendment statutory-interpretation 1. Does § 922(g)(1) violate the Second Amendment facially? 2. Does § 922(g)(1) violate the Second Amendment as applied to individuals with conviction…
25-198 Virginia Duncan, et al. v. Rob Bonta, Attorney General of California Ninth Circuit 2025-08-19 Pending Amici (6)Relisted (12) ammunition-ban common-use firearms-regulation property-rights second-amendment takings-clause 1. Whether a ban on the possession of exceedingly common ammunition feeding devices violates the Second Amendment. 2. Whether a law dispossessing cit…
25-5343 Kendrick Jarrell Beaird v. United States Fifth Circuit 2025-08-13 Pending Relisted (6)IFP constitutional-law criminal-procedure federal-sentencing-guidelines firearms-regulation second-amendment statutory-interpretation I. Whether 18 U.S.C. § 922(g)(1) comports with the Second Amendment? II. Whether Stinson v. United States still accurately state the level of deferen…
25-5228 Geber Soto v. United States Fifth Circuit 2025-07-29 Denied Response WaivedIFP constitutional-challenge criminal-prosecution firearms-regulation legal-standing second-amendment statutory-interpretation 1. Whether the government's prosecution of petitioner under 18 U.S.C. § 922(a)(1)(A) violates the Second Amendment on its face. 2. Whether the govern…
25A91 William Collins, III v. Pamela Jo Bondi, Attorney General, et al. Fourth Circuit 2025-07-23 Presumed Complete as-applied-challenge felon-in-possession firearms-regulation gun-rights second-amendment self-defense Question not identified.
25-24 Joshua Clay McCoy, Individually and on Behalf of All Others Similarly Situated as a Class, et al. v. Bureau of Alcohol, Tobacco, Firearms, and Explosives, et al. Fourth Circuit 2025-07-08 Pending Amici (3) age-restriction constitutional-rights federal-law firearms-regulation gun-purchase second-amendment 1. Whether federal laws banning 18-to-20-year-olds from purchasing handguns from federally licensed of the right to keep arms. 2. pursuant to Fed. R.…
24-1259 Jamond M. Rush v. United States Seventh Circuit 2025-06-10 Denied Amici (1)Response RequestedResponse WaivedRelisted (2) constitutional-rights firearms-regulation lawful-possession second-amendment short-barreled-rifles unregistered-weapons Whether the Second Amendment secures the right to possess unregistered short-barreled rifles that are in common use for lawful purposes.
24-7369 Shawn K. Bever v. United States Fourth Circuit 2025-06-06 Denied Response WaivedIFP bruen-test constitutional-rights firearms-regulation law-abiding-citizen second-amendment self-defense In New York State Rifle & Pistol Ass'n v. Bruen, 597 U.S. 1 (2022), this Court adopted a two-step approach for analyzing whether regulation of the pos…
24A1191 Virginia Duncan, et al. v. Rob Bonta, Attorney General of California Ninth Circuit 2025-06-04 Presumed Complete en-banc-review firearms-regulation magazine-capacity second-amendment self-defense strict-scrutiny Question not identified.
24-782 Bob Jacobson, Individually and in His Official Capacity as Commissioner of the Minnesota Department of Public Safety v. Kristin Worth, et al. Eighth Circuit 2025-01-23 Denied age-restriction constitutional-rights firearms-regulation historical-analysis public-carry second-amendment Minnesota allows young people significant access to firearms. Young people can use guns under the supervision of an adult at any age, and they can u…
24A714 Andrew Hanson, et al. v. District of Columbia, et al. District of Columbia 2025-01-21 Presumed Complete bruen-test firearms-regulation historical-analogues large-capacity-magazines second-amendment text-and-history-test Question not identified.
24-6326 Mark Allen Hayden v. United States Fifth Circuit 2025-01-16 Denied Response WaivedIFP categorical-approach circuit-split criminal-law firearms-regulation second-amendment statutory-interpretation Whether Floyd v. State, __ S.W.3d___, 2024 WL 4757855 (Tex. Crim. App. November 13, 2024) — issued by the Texas Court of Criminal Appeals after the de…
24-6158 Elden Don Brannan v. United States Fifth Circuit 2024-12-17 Denied Response RequestedResponse WaivedRelisted (2)IFP criminal-prosecution destructive-device firearms-regulation military-ordinance statutory-interpretation weapon-design Whether the Act's instruction that the term destructive device "shall not include any device which is neither designed nor redesigned for use as a wea…
24-5700 Andersen Rable v. United States Eleventh Circuit 2024-10-03 Denied Response RequestedResponse WaivedRelisted (3)IFP atf-interpretation criminal-procedure evidence-admissibility federal-firearms-license firearms-regulation mens-rea 1. Whether the District Court, Erred When It Refused to Allow Evidence of the Fact That the Bureau of Alcohol Tobacco and Firearms (hereinafter ATF), …
24-373 Maryland Shall Issue, Inc., et al v. Wes Moore, Governor of Maryland, et al. Fourth Circuit 2024-10-02 Denied Amici (2) constitutional-challenge firearms-regulation gun-rights handgun-license maryland-law second-amendment Whether Maryland's Handgun Qualification License Requirement violates the Second Amendment.
24-203 David Snope, et al. v. Anthony G. Brown, in His Official Capacity as Attorney General of Maryland, et al. Fourth Circuit 2024-08-23 Denied Amici (10)Relisted (16) constitutional-rights firearms-regulation gun-ban second-amendment semiautomatic-weapons state-law Whether the Constitution permits the State of Maryland to ban semiautomatic rifles that are in common use for lawful purposes, including the most popu…
24-5151 Tyrone Scott Cameron v. United States Eighth Circuit 2024-07-26 Denied Response WaivedIFP 2nd-amendment bruen-decision constitutional-rights conviction criminal-procedure felon-in-possession firearms-regulation new-york-state-rifle-pistol-association-v-bruen second-amendment united-states-v-jackson united-states-v-rahimi PETITIONER'S CONVICTION VIOLATES HIS SECOND AMENDMENT RIGHTS TO BEAR ARMS AND POSSESS AMMUNITION AS EXPANDED BY THE COURT IN New York State Rifle & Pi…
23A1068 Lorenzo Garod Pierre v. United States Eleventh Circuit 2024-05-30 Presumed Complete bruen-standard constitutional-challenge felon-in-possession firearms-regulation prior-precedent second-amendment Question not identified.
23-7402 Dequon Reon Stovall v. United States Fifth Circuit 2024-05-07 Denied Response WaivedIFP 2nd-amendment constitutional-challenge criminal-law criminal-possession due-process federal-jurisdiction firearms firearms-regulation interstate-commerce second-amendment statutory-interpretation Whether 18 U.S.C. § 922(g) permits conviction for the possession of any ammunition that has ever crossed state lines at any time in the indefinite pas…
23A980 Christopher Paris, Commissioner, Pennsylvania State Police v. Madison M. Lara, et al. Third Circuit 2024-05-02 Presumed Complete age-restriction bruen-test concealed-carry firearms-regulation historical-tradition second-amendment Question not identified.
23-1010 Gun Owners of America, Inc., et al. v. Kwame Raoul, Attorney General of Illinois, et al. Seventh Circuit 2024-03-14 Denied Relisted (7) 2nd-amendment bruen-decision civil-rights constitutional-interpretation due-process firearms-ban firearms-regulation gun-rights military-weaponry second-amendment standing takings Whether Illinois' categorical ban on millions of the most commonly owned firearms and ammunition magazines in the nation, including the AR-15 rifle, v…
23-995 Nadine Gazzola, et al. v. Kathleen Hochul, Governor of New York, et al. Second Circuit 2024-03-12 Denied 2nd-amendment bruen-precedent civil-procedure constitutional-standing due-process firearms-regulation free-speech preliminary-injunction regulatory-overburden second-amendment standing takings Did the Second Circuit err in the Winter analysis of Petitioners' request for preliminary injunctive relief under Fed. R. Civ. P. 65, including (1.) w…
23-6842 Reginald Creshawn Doss v. United States Eighth Circuit 2024-02-27 GVR Relisted (2)IFP 2nd-amendment bruen-test circuit-split civil-rights constitutional-challenge criminal-procedure due-process felon-in-possession firearms-regulation second-amendment standing Whether, as the Eighth Circuit held, 18 U.S.C. § 922(g)(1) (which prohibits any felon from possessing firearms) is invariably constitutional both faci…
23-880 National Association for Gun Rights, et al. v. City of Naperville, Illinois, et al. Seventh Circuit 2024-02-15 Denied Relisted (7) 2nd-amendment civil-rights common-use constitutional-rights due-process firearms-regulation founding-era handgun-ban heller-precedent heller-vs-dc second-amendment semi-automatic-weapons 1. Is the State of Illinois' ban of certain handguns constitutional in light of the holding in D.C. v. Heller, 554 U.S. 570 (2008), that handgun bans …
23-863 Dominic Bianchi, et al. v. Anthony G. Brown, in His Official Capacity as Attorney General of Maryland, et al. Fourth Circuit 2024-02-12 Denied Amici (1) 2nd-amendment bruen civil-rights common-use constitutional-rights due-process firearms-regulation gun-ownership heller individual-liberty second-amendment self-defense Whether the Constitution allows the government to prohibit law-abiding, responsible citizens from protecting themselves, their families, and their hom…
23-6520 Gary Von Bennett v. United States Fifth Circuit 2024-01-22 Denied Response WaivedIFP commerce-clause congressional-power federal-authority federal-criminal-law firearm-regulation firearms-regulation interstate-commerce scarborough-v-united-states statutory-interpretation united-states-v-lopez Whether 18 U.S.C. §922(g) should be construed to require a more substantial connection to interstate commerce than the mere passage of a firearm acros…
23-6285 Kenneth Paiva v. United States Fifth Circuit 2023-12-18 Denied Response WaivedIFP 2nd-amendment commerce-clause constitutional-limits criminal-law federal-criminal-law federal-jurisdiction firearms firearms-regulation legislative-power statutory-interpretation Whether 18 U.S.C. § 922(g) (1), which criminalizes possession of a firearm by a convicted felon, exceed s Congress's power under the Commerce Clause .
23-62 Merrick B. Garland, Attorney General, et al. v. Scott A. Hardin Sixth Circuit 2023-07-21 Denied Relisted (3) administrative-law atf-rule automatic-weapon bump-stock due-process firearms-regulation machinegun-definition mass-shootings second-amendment statutory-interpretation Whether a bump stock device is a "machinegun" as defined in 26 U.S.C. 5845(b) because it is designed and intended for use in converting a rifle into a…
22-976 Merrick B. Garland, Attorney General, et al. v. Michael Cargill Fifth Circuit 2023-04-07 Judgment Issued Amici (21)Relisted (4) 2nd-amendment administrative-law atf atf-rule bump-stock firearms firearms-regulation machinegun-definition national-firearms-act statutory-interpretation trigger-mechanism Whether a bump stock device is a "machinegun" as defined in 26 U.S.C. 5845(b) because it is designed and intended for use in converting a rifle into a…
22-622 Nadine Gazzola, et al. v. Kathleen Hochul, Governor of New York, et al. Second Circuit 2023-01-09 Denied 2nd-amendment civil-rights constitutional-rights dealer firearms firearms-regulation government-overreach licensing-scheme natural-resources-defense-council second-amendment standing winter-standard 1. Is there a likelihood of success on the merits under Winter v. Natural Resources Defense Council that the meaning and purpose of "to keep," as in…
22-6420 Rodney Deangelo Jordan v. United States Fifth Circuit 2022-12-29 Denied Response WaivedIFP commerce-clause constitutional-authority constitutional-limits criminal-law federal-power felon-possession firearms-regulation police-power statutory-interpretation Whether, when enacting the Unlawful Felon in Possession of a Firearm statute (18 U.S.C. § 922(g)), Congress exceeded its authority to act?
21-8060 Darrell Cordell Williams v. United States Fifth Circuit 2022-06-06 Denied Response WaivedIFP commerce-clause constitutional-authority constitutional-limits federal-power felon-in-possession firearms-regulation police-power second-amendment statutory-interpretation Whether, when enacting the Unlawful Felon in Possession of a Firearm statute (18 U.S.C. § 922(g)), Congress exceeded its authority to act?
21-902 Dominic Bianchi, et al. v. Brian Frosh, Attorney General of Maryland, et al. Fourth Circuit 2021-12-20 GVR Amici (5)Response RequestedResponse WaivedRelisted (3) 2nd-amendment arms-possession civil-rights constitutional-rights due-process firearms firearms-regulation heller-precedent second-amendment self-defense standing takings Whether the Constitution allows the government to prohibit law-abiding, responsible citizens from protecting themselves, their families, and their hom…
21-5455 Emmanuel Granados v. United States Fifth Circuit 2021-08-24 Denied Response WaivedIFP 2nd-amendment commerce-clause congressional-power constitutional-limits criminal-law federal-power firearms firearms-regulation statutory-interpretation Whether 18 U.S.C. § 922(g), which criminalizes possession of a fire arm by a convicted felon, exceed s Congress's power under the Commerce Clause.
20-7502 Vaughn Alexander Cropper v. United States Eleventh Circuit 2021-03-19 Denied IFP 2nd-amendment appellate-review civil-rights constitutional-challenge criminal-indictment criminal-procedure due-process federal-jurisdiction firearms-regulation Second-Amendment standing statutory-interpretation Question not identified.
20-7301 Bernandino Gawala Bolatete v. United States Eleventh Circuit 2021-03-02 Denied Response WaivedIFP 2nd-amendment article-i congress-power-to-tax congressional-power criminal-law criminal-punishment firearms-regulation national-firearms-act suppressor-registration taxation-clause tenth-amendment Petitioner was convicted under 26 U.S.C. §§ 5861(d) and 5871, sections of the National Firearms Act that impose criminal penalties of up to 10 years' …
20-6964 Dallas Ray Morales v. United States Fifth Circuit 2021-01-28 Denied Response WaivedIFP ammunition-possession commerce-clause constitutional-challenge criminal-law due-process federal-criminal-law federal-jurisdiction firearms firearms-regulation interstate-commerce statutory-interpretation Whether 18 U.S.C. §922(g) permits conviction for the possession of any ammunition that has ever crossed state lines at any time in the indefinite past…
19-704 Matthew D. Wilson, et al. v. Cook County, Illinois, et al. Seventh Circuit 2019-12-03 Denied Amici (1)Relisted (7) 2nd-amendment civil-rights common-use common-use-test due-process firearms-regulation heller heller-precedent local-government-restriction second-amendment self-defense standing takings This Court has held that the Second Amendment "guarantee[s] the individual right to possess and carry weapons in case of confrontation." District of C…
19-6220 Nerses Nick Bronsozian v. United States Ninth Circuit 2019-10-09 GVR IFP 2nd-amendment commerce-clause constitutional-interpretation criminal-prosecution due-process firearms firearms-regulation national-firearms-act registration statutory-construction taxation taxation-power When the National Firearms Act ("NFA") was passed in 1934, the sole constitutional authority for the law was Congress's power to tax under U.S. Const.…
18-9104 Kurt Zamor v. United States Eleventh Circuit 2019-05-02 Denied Response WaivedIFP appellate-procedure common-carrier criminal-procedure criminal-procedure-rule-16 evidence evidence-sufficiency expert-testimony firearms firearms-regulation mens-rea sentencing sentencing-review statutory-interpretation I. WHETHER THE ELEVENTH CIRCUIT FAILED TO PROPERLY APPLY TITLE 18 U.S.C. SECTION 922(e) IN DETERMINING WHETHER THE EVIDENCE WAS SUFFICIENT TO ESTABLIS…
18-7451 Shane Cox v. United States Tenth Circuit 2019-01-16 Denied Relisted (2)IFP affirmative-defense criminal-procedure due-process due-process-right-to-present-defense federal-preemption federal-prosecution firearms-regulation kansas-law second-amendment short-barreled-rifles silencers state-rights I. Did the district court deny Mr. Cox his due process right to present a defense when it precluded Mr. Cox from arguing to the jury that his reliance…
18-6771 Johny Gardner v. United States Fifth Circuit 2018-11-21 Denied Response RequestedResponse WaivedRelisted (2)IFP 2nd-amendment commerce-clause congressional-power constitutional-interpretation criminal-law federal-jurisdiction felon-in-possession firearms firearms-regulation second-amendment statutory-interpretation Whether 18 U.S.C. § 922(g), which criminalizes possession of a firearm by a convicted felon, exceeds Congress's power under the Commerce Clause.
18-663 Fredric Russell Mance, Jr., et al. v. William P. Barr, Attorney General, et al. Fifth Circuit 2018-11-21 Denied Amici (6)Relisted (8) 2nd-amendment constitutional-rights due-process equal-protection federal-firearms-licensees firearm-sales firearms-regulation handgun-sales interstate-commerce second-amendment standing Federal law bars consumers from acquiring handguns outside their home state. This prohibition limits choice and price competition, and forces many han…
18-318 Christos Koutentis v. New York City Police Department, Licensing Division New York 2018-09-12 Denied Response Waived administrative-law civil-rights constitutional-rights due-process firearms-permit firearms-regulation licensing nypd-regulations revocation second-amendment vagueness void-for-vagueness Do the N.Y.P.D. regulations, as applicable to the revocation of a firearms permit, violate the Petitioner's rights under the Second Amendment? Are th…
18-5541 Darren Kyle Stepp-Zafft v. United States Eighth Circuit 2018-08-14 Denied Response WaivedIFP 2nd-amendment commerce-clause congressional-power criminal-penalty due-process firearms-regulation national-firearms-act nfa-firearms right-to-bear-arms second-amendment tax taxation united-states-constitution Is 26 U.S.C. § 5861(d) a valid exercise of Congress's power to tax?