The White House is having a hard time wrapping up its efforts to design a voluntary code of conduct for companies doing business in China. Among other things, the code would help companies avoid purchasing products made by prison labor. It was supposed to be in place by midsummer to help blunt congressional moves to hike tariffs on goods made by China's military and some state industries. But companies fear lawmakers will make any completed code mandatory as part of a sanctions bill. So business is dragging its heels in talks with the White House.