The Securities and Exchange Commission is responsible for interpreting and enforcing Section 28(e). In Section 28(e) the definition of qualifying services is detailed and explicit, but Section 28(e) is not a rule it is just a "safe harbor". The use of client commissions to pay for services which are not within the safe harbor of Section 28(e) is not within the safe harbor. A fiduciary who "pays up" in client commissions to receive non-qualifying services must be able to defend this practice under applicable law. For pension plans subject to ERISA, a fiduciary can use client assets only for the exclusive benefit of clients and cannot use the client assets for the fiduciary's benefit. Most public pension plans have similar prohibitions. For registered investment companies (such as mutual funds), Section 17(e)(1) of the Investment Company Act of 1940 generally prohibits a fund affiliate—such as the fund adviser—receiving compensation when purchasing or selling property for a registered fund. As a result, for all practical purposes, brokerage arrangements for pension plans and registered investment companies must come within the Section 28(e) safe harbor or run afoul of these restrictions.