A federal judge Wednesday struck down a section of the law linking draft registration to financial aid.

District Judge Robert E. Keeton issued a preliminary opinion that said it was unconstitutional to force women and those students ineligible for the draft to complete registration compliance forms.

In 1983 Congress passed the Solomon amendment, which requires that all eligible males register for the draft in order to receive federal financial aid, and authorized the Department of Education to deny funding to students not complying with the amendment.

Keeton's decision only affects students not eligible for the draft. His opinion said that students who have otherwise met all requirements for financial aid would not--under the Department of Education regulations--b, denied that aid.

The Keeton case hinges on regulations that were never authorized by Congress, not the constitutionality of the amendment itself, said William G. Southard, a lawyer who argued against the regulations together with the Civil Liberties Union of Massachusetts.

The case concerned three Boston University students, two men and a woman, who could not complete the compliance certificate because of religious restrictions.

The students, all members of the United Methodist Church, face the threat of not receiving aid.

Southard hopes the Keenan case will promote a nationwide injunction to protect students so that they will not be denied aid on the basis of religious beliefs that do not comply with conscription.

A Minnesota court challenged the Solomon amendment last March in a case which is now before the United States Supreme Court. That court judged the amendment unconstitutional.