In the wake of Donald Sterling's comments and subsequent punishment by the NBA, the league has decided to unseal its constitution and bylaws, putting them online for all to see.
There was some speculation that the league constitution prohibited commissioner Adam Silver from terminating Donald Sterling as owner of the Los Angeles Clippers, but the contents of the constitution support Silver's decision to fine Sterling the maximum possible amount ($2.5 million) and ban him for life.
The 92-page document is linked below. If you're curious, the section on the termination of ownership is Article 13, 'TERMINATION OF OWNERSHIP OR MEMBERSHIP'. The section is on page 26 of the constitution, which translates to page 37 of the PDF file.