Copyright and Royalties
Many white labels contain unsolicited remixes and/or tracks that are not yet licensed or released (also called "bootlegs"). White labels can be referred to as "promos" (short for "promotional copies") that many top-name DJs receive and play weeks or months prior to the day of general release to the public. As artists using samples pay high fees for the privilege of such, they must be able to gauge the market potential of their tracks prior to approval. Recently, smaller promo services offer record companies a more economical means of distribution although these companies may not have the means to properly protect releases from illegal copying.
The industry itself seems to be aware of this necessity and white labels are commonly accepted as a necessary evil within the industry, which has only prosecuted a small number of those artists using white labeled pressings of uncleared samples and compositions. Some white labels are recalled after the promotional period (except from top-name DJs and radio stations).
Read more about this topic: White Label