Legal issues have held up the planned release of Doom 3 source code.
According to a Tweet from id Software co-founder John Carmack, as reported by Shack News, the studio's lawyers are concerned about the patent for a stencil shadowing technique used in the game known as 'Carmack's Reverse'.
"Lawyers are still skittish about the patent issue around 'Carmack's Reverse,' so I am going to write some new code for the Doom 3 release," he explained.
Carmack didn't mention exactly how long that might take.
Id announced its decision to make the code public at this year's Quakecon, explaining that it hoped it would help aspiring developers learn their trade.