My brother and I shall inherit from our father who has just passed away. As the guardian of my weaker adult brother, am I required to go to the judge to accept the inheritance on his behalf?

No, if the value of the estate's assets is clearly greater than the amount of the debts, you can simply accept the inheritance without the judge's authorization.

However, you must first and foremost obtain a certificate drawn up by the notary in charge of settling the succession establishing that the assets are much greater than the liabilities (article 507-1 of the Civil Code). In other cases, you will have to submit a request for authorization of simple acceptance of the succession with the guardianship judge using the cerfa n°15911*04 form.