15 U.S. Code § 77iii - Effective time of qualification
After qualification has become effective as to the indenture under which a security has been or is to be issued, no stop order shall be issued pursuant to section 77h(d) of this title, suspending the effectiveness of the registration statement relating to such security or of the application for qualification of such indenture, except on one or more of the grounds specified in section 77h of this title, or the failure of the issuer to file an application as provided for by section 77eee(b)(2) of this title.
The making, amendment, or rescission of a rule, regulation, or order under the provisions of this subchapter (except to the extent authorized by subsection (a) of section 77nnn of this title with respect to rules and regulations prescribed pursuant to such subsection) shall not affect the qualification, form, or interpretation of any indenture as to which qualification became effective prior to the making, amendment, or rescission of such rule, regulation, or order.
No trustee under an indenture which has been qualified under this subchapter shall be subject to any liability because of any failure of such indenture to comply with any of the provisions of this subchapter, or any rule, regulation, or order thereunder.
Nothing in this subchapter shall be construed as empowering the Commission to conduct an investigation or other proceeding for the purpose of determining whether the provisions of an indenture which has been qualified under this subchapter are being complied with, or to enforce such provisions.