{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,4,17]],"date-time":"2026-04-17T04:41:34Z","timestamp":1776400894721,"version":"3.51.2"},"posted":{"date-parts":[[2026]]},"group-title":"SSRN","reference-count":9,"publisher":"Elsevier BV","content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":[],"abstract":"<jats:p>Do policy reversals restore market microstructure? I study the U.S. Supreme Court\u2019s February 20, 2026 ruling in Learning Resources v. Trump, which invalidated the 2025 IEEPA tariff regime. Using NASDAQ TotalView Level 3 data for 20 tariff-sensitive and 8 control stocks, I implement a difference-in-differences design around the ruling. I find no statistically or economically significant change in order book dynamics: median order lifetimes decline by -27.7ms for tariff stocks (t = -0.87), with a DiD estimate of -7.7ms relative to controls. The ruling-day movement is only 0.77 standard deviations of placebo variation, indicating that it lies well within normal daily fluctuations. Because the analysis window precedes the announcement, the null result implies that the ruling was fully anticipated and incorporated into order book behavior prior to its release. These findings are consistent with microstructure hysteresis: policy-induced disruptions persist even after formal reversal. The results suggest that legal interventions may be insufficient to restore pre-shock liquidity conditions once market participants have adapted.<\/jats:p>","DOI":"10.2139\/ssrn.6592832","type":"posted-content","created":{"date-parts":[[2026,4,17]],"date-time":"2026-04-17T03:45:07Z","timestamp":1776397507000},"source":"Crossref","is-referenced-by-count":0,"title":["Did the Supreme Court Restore Order Book Normalcy?,Microstructure Evidence from Learning Resources v. Trump"],"prefix":"10.2139","author":[{"ORCID":"https:\/\/orcid.org\/0009-0005-8477-9393","authenticated-orcid":true,"given":"Boon Chuan","family":"Lim","sequence":"first","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"78","reference":[{"key":"ref1","doi-asserted-by":"crossref","first-page":"2267","DOI":"10.1093\/rfs\/hhu032","article-title":"High-frequency trading and price discovery","volume":"27","author":"J Brogaard","year":"2014","journal-title":"Review of Financial Studies"},{"key":"ref2","doi-asserted-by":"crossref","first-page":"335","DOI":"10.1111\/jofi.12302","article-title":"News trading and speed","volume":"71","author":"T Foucault","year":"2016","journal-title":"Journal of Finance"},{"key":"ref3","doi-asserted-by":"crossref","first-page":"357","DOI":"10.2307\/1912559","article-title":"A new approach to the economic analysis of nonstationary time series and the business cycle","volume":"57","author":"J D Hamilton","year":"1989","journal-title":"Econometrica"},{"key":"ref4","doi-asserted-by":"crossref","DOI":"10.1016\/j.ribaf.2025.102925","article-title":"Tariff exposure and sectoral vulnerability","volume":"77","author":"T Kaczmarek","year":"2025","journal-title":"Research in International Business and Finance"},{"key":"ref5","doi-asserted-by":"crossref","first-page":"967","DOI":"10.1111\/jofi.12498","article-title":"The Flash Crash","volume":"72","author":"A Kirilenko","year":"2017","journal-title":"Journal of Finance"},{"key":"ref6","year":"2026","journal-title":"Order book dynamics during the Liberation Day tariff shock. Working paper"},{"key":"ref7","first-page":"15","article-title":"The Adaptive Markets Hypothesis","volume":"30","author":"A W Lo","year":"2004","journal-title":"Journal of Portfolio Management"},{"key":"ref8","doi-asserted-by":"crossref","first-page":"712","DOI":"10.1016\/j.finmar.2013.06.006","article-title":"High frequency trading and the new-market makers","volume":"16","author":"A J Menkveld","year":"2013","journal-title":"Journal of Financial Markets"},{"key":"ref9","doi-asserted-by":"crossref","first-page":"86","DOI":"10.1016\/j.jfineco.2016.06.001","article-title":"Sovereign credit risk, liquidity, and ECB intervention","volume":"122","author":"L Pelizzon","year":"2016","journal-title":"Journal of Financial Economics"}],"container-title":[],"original-title":[],"deposited":{"date-parts":[[2026,4,17]],"date-time":"2026-04-17T03:46:48Z","timestamp":1776397608000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.ssrn.com\/abstract=6592832"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2026]]},"references-count":9,"URL":"https:\/\/doi.org\/10.2139\/ssrn.6592832","relation":{},"subject":[],"published":{"date-parts":[[2026]]},"subtype":"preprint"}}