Section 43 seems to refer to the Lanham Act of 1946 that established trademark law, prohibiting using similar logos, names or false advertising in order to lure clients of a product. Pop art, led by Andy Warhol, had represented Campbell's Soup cans in challenge of this law. The law would later be challenged through the hip hop genre when songs began to be built through sampling previous music. However, I don't think there's any "stolen goods" in this instrumental, so I'm not sure about the relevancy of the title.
With its several "movements" Section 43 takes the listener through a variety of moods. The song starts out with a slow jam, acidic organ and electric guitar. The B section follows with a different melody in which the organ and electric guitar play in unison. The C section slows down, mellows, the organ is a bit softer, the electric guitar is picked note for note rather than strummed. Back to the original A, but this time with a harmonica rather than an electric guitar, which grows in intensity. The next D section is full comedy for merely a moment, out of tune, out of rhythm, before turning into a loud A jam of organ and electric guitar. After a fade, we return to the slow C section produced much like the first time around, except eventually a harmonica is added, playing chords until the tune winds down with accents from a soft reverberating electric guitar. The whole thing takes about seven minutes, one of the longest of the instrumentals produced in this collection of psychedelic music.