18 U.S. Code § 333 - Mutilation of national bank obligations
Whoever mutilates, cuts, defaces, disfigures, or perforates, or unites or cements together, or does any other thing to any bank bill, draft, note, or other evidence of debt issued by any national banking association, or Federal Reserve bank, or the Federal Reserve System, with intent to render such bank bill, draft, note, or other evidence of debt unfit to be reissued, shall be fined under this title or imprisoned not more than six months, or both.
(June 25, 1948, ch. 645, 62 Stat. 700; Pub. L. 103–322, title XXXIII, § 330016(1)(B), Sept. 13, 1994, 108 Stat. 2146.)
edit: adding more info to ease your minds a bit…
From a long running campaign about stamping political messages on Federal Reserve Notes.
These bills are clearly intended to remain in circulation. If you're redacting the serial numbers or pulling out the security strips, that would be different. Scrawling a short message? Never been a problem.
…and put the following part of the quote in bold…
with intent to render such bank bill, draft, note, or other evidence of debt unfit to be reissued
This is obviously intended to be a political statement and the person doing it obviously intends the bills to stay in circulation in order to spread that statement.
Intent is apparently the key issue here.
edit: adding more info to ease your minds a bit…
From a long running campaign about stamping political messages on Federal Reserve Notes.
https://www.stampstampede.org/faq/yes-its-legal/
https://www.stampstampede.org/uploads/alan-levine-nov-6-opinion.pdf
These bills are clearly intended to remain in circulation. If you're redacting the serial numbers or pulling out the security strips, that would be different. Scrawling a short message? Never been a problem.
Hence why I said…
…and put the following part of the quote in bold…
This is obviously intended to be a political statement and the person doing it obviously intends the bills to stay in circulation in order to spread that statement.
with "intent" it really depends who's the judge... or perhaps who appointed them.