Senior Clark County District Court Judge Charles Thompson says if Kucinich is excluded, he'll issue an injunction stopping the televised debate.
The judge sided with a lawyer for the Ohio congressman, who says debate host MSNBC at first invited Kucinich to take part and then told him last week he couldn't.
A lawyer for the network says MSNBC decided to go with the top three candidates after the Iowa and New Hampshire primaries.
The judge calls it a matter of fairness and says Nevada voters will benefit if they hear from more than just, and .
The cable network and the Democratic Party are calling the 6 p.m. debate a chance to hear issues from Nevada's minority communities. Tim Russert and Brian Williams are moderating.