貸主が過払金を返還しないで新たな貸付けをした場合について，2007年2月13日以降の一連の最高裁判決は，「過払金充当合意が存在しなければ，貸主は新たな貸付額の全部を元本として返還請求できる」と判断した。しかし，1964年11月18日の最高裁判決を基礎にして，「利息制限法2条の解釈により，貸主が元本として返還請求できるのは，新たな貸付金から過払金を差し引いた金額に限られる」と解釈すべきであった。貸金業者に対する過払金返還請求訴訟は，なくなっていくだろう。しかし今後は，金融機関に対する借入金債務も含めて，利息と元本への充当が広い範囲で問題になってくると考えられる。その際には，1964年11月18日の判例理論を継承・発展させるべきである。 On February 13, 2007 and subsequent dates, the Japanese Supreme Court decreed that, in cases where a lender lends money at a high interest rate ("excess interest") without reimbursing the borrower for money that the borrower claims is an "overpayment," "Unless there was a prior agreement between the lender and the borrower that money recognized by both parties as an 'overpayment' would be reimbursed, the lender may demand total reimbursement of the principal". Therefore, this 2007 Supreme Court decree supersedes a ruling by the Supreme Court made on November 18, 1964, that, when there has been more than one loan made to a borrower, "the lender may only demand that the borrower pay back the principal, not anything recognized as an 'overpayment.'" Thus, it seems likely that litigation by borrowers for reimbursement of overpayment against moneylenders will gradually wane. However, in the future, the problem of appropriate amounts of reimbursement―that is, how much the principal is and how much more money besides the principal should be paid back by the debtor (including debts paid back to financial institutions), will become increasingly complex and might lead again to litigation. If this happens, the Supreme Court will have to expand on and further develop the judgment the Supreme Court made on November 18, 1964.
