As house prosecutors open their case in the Senate for President Clinton's removal from office, prosecution and defense trial briefs make each side's strategy clear. House Judiciary Committee Chairman Henry Hyde (R) of Illinois and his team argue that the president committed perjury before a federal grand jury and obstructed justice; they give several examples. They argue that perjury and obstruction of justice are high crimes and misdemeanors that warrant removal from office. The president's lawyers continue to insist that the president did not lie in his grand-jury testimony about what he said when deposed in the Paula Jones sexual-harassment case. The crux of this dubious argument is that the president believed his answers in the January 1998 deposition were true under the definition of sexual relations that the plaintiff's lawyers showed him. The president's case on the obstruction of justice charges, where his team is able to dispute the prosecution's version of the facts and their interpretation, is far stronger than his case concerning perjury. The House maintains that several federal judges have been impeached for perjury, even when it did not involve their official duties, and that the standard for a president is the same. Mr. Clinton's team says the two are apples and oranges - that impeachment is the only way to remove unelected federal judges from office, whereas the bar must be set higher for presidents, who are elected for a limited term. In addition, they hold that the private perjuries of certain federal judges - unlike the perjury Clinton is alleged to have committed - in fact did bear on their ability to perform their official duties. The president's lawyers say the House would remove him because he had a wrongful relationship and tried to cover it up. The House says that the heart of the case is not private sexual conduct but lying under oath and obstructing justice. Presidential lawyers also argue that the articles of impeachment are unconstitutional. They say the bundling of unspecific multiple charges could result in different groups of senators voting for different parts of each article, resulting in a two-thirds vote to convict, but without two-thirds of senators actually agreeing on any one charge. Finally, each side casts the outcome in the starkest terms. The House argues that if the president is not convicted for this conduct, no House will ever be able to impeach again and no Senate will ever convict. The White House replies that removing the president under these circumstances would seriously weaken the presidency and alter the constitutional balance of powers. Such arguments are predictable, and neither stark outcome is foreordained. Senators, in their role as jurors, must now act with discretion and listen to each side's presentation. Their understanding of the issues will be crucial when the time comes to vote on motions to call witnesses or dismiss the case.