The trustee's power is set by the trust instrument. If the trust instrument says he has the power to sell real property with or without consent of the beneficiaries, perhaps he does have the power. But the law also imposes fiduciary duty on the part of the trustee to act with utmost care and good faith toward the beneficiaries. I can't say if he did anything wrong without examining the trust instrument.
The power to sell real estate is typically granted to a successor trustee under the trust document. Unless the document itself requires approval of the beneficiaries, the trustee can sell the property without consulting you, with the caveat that the trustee has a fiduciary duty to the beneficairies and must act in their best interest.
However, you can petition the Court for an order preventing a sale of real property, if you feel that such an action is in breach of his duty to you. In fact, you can petition the court to have the trustee removed if you can show he has breached his duties under the trust.
I suggest you consult a local probate attorney for more specific guidance.
Typically the trust will grant the trustee the power to sell real estate without the consent of the beneficiaries, but as the prior comments pointed out, no one can say for certain without reading the trust instrument. The trustee does have a fiduciary duty to act in the best interest of all the beneficiaries, but the courts will allow a significant degree of discretion with respect to those actions and any claim against the trustee for breach of fiduciary duty must be well documented and supported by significant evidence.
On another note, I noticed you state you are a beneficiary, but you did not indicate whether the grantor of the trust is deceased. In providing the above answer, I assume the grantor is deceased, but if not, the outcome is entirely different. In any event, I suggest you get with a local estate/probate attorney to discuss the alleged breaches of fiduciary duty and your potential remedies.
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