The fight over federal subsidies to public interest groups intervening in regulatory proceedings was renewed yesterday on the first day of hearings before a House judiciary sub-committee.

Judiciary committee chairman Peter Rodino (D-N.J.) and Edward Kennedy (D.-Mass.), author of a similar bill in the Senate, called the legislation a means for consumers to participate as effectively as large corporations and trade associations in rule and rate-making that affects them. Conservative opponents labeled it a bill to enrich Washington lawyers.

The legislation would authorized federal agencies to grant $10 million over a three-year period to groups, including lawyers and expert witnesses, that can make a "substantial" contribution to the procedures and that have a small economic interest in the outcome or that do not have enough funds to enable them to participate. Another $2 million would be granted by the courts to reimburse the legal costs of persons who win lawsuits in which there is a public interest. A similar bill was reported out of a Senate committee last year but never was voted on.

The concept, which has White House endorsement, represents official admission that the regulatory agencies fail to consider and protect adequately the interests of all the people - not just those they regulate. A few agencies, such as the Consumer Product Safety Commission and the Federal Energy Administration, have begun to pay public witnesses on their own.

Conservative Republican Carlos J. Moorhead of California expressed opposition to the subsidies because groups coming to Washington to lobby represent minority rather than majority views.